Hello,

I am writing a software that uses MIP solvers interchangeably and I would like to include SCIP as an option.

I have been looking for an example of how to build a problem and run it without much luck.

The documentation points nowhere, and the MIP example is about reading files. Not exactly what I need.

To be precise:

I would like to pass all the problem information by memory using C-style functions since I need to link scip dynamically.

An example of what I need, but using Highs is this.

Any help figuring how to interface SCIP from C is appreciated.

Hello,

SCIPcolGetNLPNonz() returns the number of LP rows a column appears in and SCIPcolGetNNonz() (call this nnz) is the total number of rows a column appears in. SCIPcolGetRows() (call this total) returns an array of rows that a column appears in. In my tests I observed that the first nnz rows returned by this function are in the LP and the remaining (total - nnz) rows are not in the LP. I was wondering if this is always true. Similarly, can we say the first set of columns returned by the SCIProwGetCols() function are in the LP and the remaining ones are not?

Thank you!

When I compile and install scipoptsuite-8.0.3 on centos7, an error occurs as follows：

[ 4%] Linking CXX executable unit_test
CMakeFiles/unit_test.dir/TestMain.cpp.o: In function Catch::TestGroupStats::~TestGroupStats()': TestMain.cpp:(.text+0xd34): undefined reference to operator delete(void*, unsigned long)'
CMakeFiles/unit_test.dir/TestMain.cpp.o: In function Catch::TestRunStats::~TestRunStats()': TestMain.cpp:(.text+0xdb4): undefined reference to operator delete(void*, unsigned long)'
CMakeFiles/unit_test.dir/TestMain.cpp.o: In function Catch::Matchers::Exception::ExceptionMessageMatcher::match(std::exception const&) const': TestMain.cpp:(.text+0xf15): undefined reference to std::__cxx11::basic_string<char, std::char_traits, std::allocator >::compare(char const*) const'
CMakeFiles/unit_test.dir/TestMain.cpp.o: In function Catch::(anonymous namespace)::parseSpecialTag(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)': TestMain.cpp:(.text+0xfc2): undefined reference to std::__cxx11::basic_string<char, std::char_traits, std::allocator >::compare(char const*) const'
TestMain.cpp:(.text+0xfd9): undefined reference to std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::compare(char const*) const' TestMain.cpp:(.text+0xff5): undefined reference to std::__cxx11::basic_string<char, std::char_traits, std::allocator >::compare(char const*) const'
TestMain.cpp:(.text+0x1011): undefined reference to std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::compare(char const*) const' CMakeFiles/unit_test.dir/TestMain.cpp.o:TestMain.cpp:(.text+0x102d): more undefined references to std::__cxx11::basic_string<char, std::char_traits, std::allocator >::compare(char const*) const' follow
CMakeFiles/unit_test.dir/TestMain.cpp.o: In function std::vector<std::__cxx11::sub_match<__gnu_cxx::__normal_iterator<char const*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >, std::allocator<std::__cxx11::sub_match<__gnu_cxx::__normal_iterator<char const*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > > >::operator=(std::vector<std::__cxx11::sub_match<__gnu_cxx::__normal_iterator<char const*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >, std::allocator<std::__cxx11::sub_match<__gnu_cxx::__normal_iterator<char const*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > > > const&) [clone .isra.0]': TestMain.cpp:(.text+0x1673): undefined reference to operator delete(void*, unsigned long)'
CMakeFiles/unit_test.dir/TestMain.cpp.o: In function Catch::ExceptionTranslatorRegistry::registerTranslator(Catch::IExceptionTranslator const*)': TestMain.cpp:(.text+0x1851): undefined reference to operator delete(void*, unsigned long)'
CMakeFiles/unit_test.dir/TestMain.cpp.o: In function void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char const*>(char const*, char const*, std::forward_iterator_tag) [clone .constprop.0]': TestMain.cpp:(.text+0x1aeb): undefined reference to std::__cxx11::basic_string<char, std::char_traits, std::allocator >::_M_create(unsigned long&, unsigned long)'
CMakeFiles/unit_test.dir/TestMain.cpp.o: In function Catch::Detail::(anonymous namespace)::StreamBufImpl<Catch::Detail::(anonymous namespace)::OutputDebugWriter, 256ul>::sync()': TestMain.cpp:(.text+0x1bb1): undefined reference to operator delete(void*, unsigned long)'
CMakeFiles/unit_test.dir/TestMain.cpp.o: In function void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char*>(char*, char*, std::forward_iterator_tag) [clone .constprop.0]': TestMain.cpp:(.text+0x1c4b): undefined reference to std::__cxx11::basic_string<char, std::char_traits, std::allocator >::_M_create(unsigned long&, unsigned long)'
CMakeFiles/unit_test.dir/TestMain.cpp.o: In function non-virtual thunk to Catch::Matchers::Exception::ExceptionMessageMatcher::match(std::exception const&) const': TestMain.cpp:(.text+0x1e95): undefined reference to std::__cxx11::basic_string<char, std::char_traits, std::allocator >::compare(char const*) const'
CMakeFiles/unit_test.dir/TestMain.cpp.o: In function Catch::ExceptionTranslatorRegistry::~ExceptionTranslatorRegistry()': TestMain.cpp:(.text+0x1f6e): undefined reference to operator delete(void*, unsigned long)'
CMakeFiles/unit_test.dir/TestMain.cpp.o: In function std::_Rb_tree<Catch::TestCase const*, Catch::TestCase const*, std::_Identity<Catch::TestCase const*>, std::less<Catch::TestCase const*>, std::allocator<Catch::TestCase const*> >::_M_erase(std::_Rb_tree_node<Catch::TestCase const*>*) [clone .isra.0]': TestMain.cpp:(.text+0x2043): undefined reference to operator delete(void*, unsigned long)'
TestMain.cpp:(.text+0x205e): undefined reference to operator delete(void*, unsigned long)' TestMain.cpp:(.text+0x2079): undefined reference to operator delete(void*, unsigned long)'
TestMain.cpp:(.text+0x209d): undefined reference to `operator delete(void*, unsigned long)'

The documentation could be served well by adding an example of how one should add a quadratic objective function. While there is documentation for the API reference, it is very difficult to parse through all the possible handlers and find the right one. For instance here: https://www.scipopt.org/doc/html/group__CONSHDLRS.php#gad3707e7f7166bea83b7713cf2e52b0db

Even from here it isnt clear how a quadratic objective function should really be defined.

(base) chengwei@chengwei-Latitude-5411:$ cd /home/chengwei/scipsdp-4.0.0
(base) chengwei@chengwei-Latitude-5411:/scipsdp-4.0.0$ mkdir lib
(base) chengwei@chengwei-Latitude-5411:/scipsdp-4.0.0$ cd lib
(base) chengwei@chengwei-Latitude-5411:/scipsdp-4.0.0/lib$ ln -s /home/chengwei/SCIPOptSuite-8.0.0-Linux/bin/scip
(base) chengwei@chengwei-Latitude-5411:/scipsdp-4.0.0/lib$ cd ..
(base) chengwei@chengwei-Latitude-5411:/scipsdp-4.0.0$ make
make/make.scipsdpproj:113: .//lib/scip/bin/scip... not found
make/make.scipsdpproj:114: *** Please compile SCIP with options LPS= SUFFIX= OSTYPE= ARCH= COMP= TPI=. Stop.
(base) chengwei@chengwei-Latitude-5411:~/scipsdp-4.0.0$

How can handle this problem?

I install SCIPOptSuite-8.0.0-Linux by precompiling sh.

Best,

Chengwei

First, thank you for the work you have done.
The version of CppAD used in SCIP (7.0.3) is 20180000.0. I tried to update the cppad folder contents inside the source codes, and it didn't work. I wonder if updating this library improves SCIP's performance? How can I update this library if there is improvement?

Mr Matthias suggested me to create an issue here. I understand that there has have already been a huge amount of issues that have been resolved with regards to installation, but something seems to be going haywire in my installation process and I am very keen to understand why and how to resolve it. Please, if you could see the my doings below.

On downloading scip-8.0.0 from the official website, and following the commands listed here: https://github.com/scipopt/scip/blob/master/INSTALL.md. I get a weird error:

-- Build shared libraries: ON
-- Build type: Release
-- Finding ZLIB
-- Finding ZLIB - found
-- Finding Readline
-- Finding Readline - found
-- Finding GMP
-- Finding GMP - found
-- Finding PAPILO
CMake Error at CMakeLists.txt:298 (find_package):
Could not find a package configuration file provided by "PAPILO" with any
of the following names:

PAPILOConfig.cmake
papilo-config.cmake
Add the installation prefix of "PAPILO" to CMAKE_PREFIX_PATH or set
"PAPILO_DIR" to a directory containing one of the above files. If "PAPILO"
provides a separate development package or SDK, be sure it has been
installed.
-- Configuring incomplete, errors occurred!

I was wondering if you could please help me resolve this?

Many thanks for your time on this.

Sorry to bring up this naive question. I have read the source code of these 2 functions and I know SCIPgetBestChild returns the best node w.r.t the node selection strategy. However, I can't understand meaning of the attribute tree->childrenprio in SCIPgetPrioChild.

1. What priority is this attribute?
2. Why does SCIP need this attribute?

Thanks a lot.

I have a simple model that has obvious symmetry. Solving the model for whatever number of Power Transformers, should be no more difficult than solving the model for just one, as the solution of one can be copied to the others. SCIP does not detect symmetry in this MINLP.

These are the variables:

These are the constraints:

For PTs = [1,2,3] (so, for 3 Power Transformers), we get the following message:

If we solve the model for 1 Power Transformer, we get this result:

For 3 Power Transformers, we get this:

Notice that the solution for 3 Transformers is 3 times the solution for 1, as it should be. (The variables are also the same) You can find the code here: not_detecting_symmetry.zip

Building a certain MILP with indicator constraints produces the following the lines of error and causes the program to crash:

ELEAVE56 ERROR! Tried to put a fixed column variable into the basis. idx=72, lower=0, upper=0
ELEAVE56 ERROR! Tried to put a fixed column variable into the basis. idx=72, lower=0, upper=0
ELEAVE56 ERROR! Tried to put a fixed column variable into the basis. idx=79, lower=0, upper=0

The underlying issue was introduced between scip version 8.0.0 to 8.0.1 (scip 8.0.0 solves the problem correctly, scip 8.0.1 produces the error).

I use pyscipopt in python 3.7 to construct the problem. Both, version 4.2.0 and 4.0.0 work fine.

Here the "writeProblem" output (identical for scip 8.0.0 and 8.0.1):

\ SCIP STATISTICS
\   Problem name     : model
\   Variables        : 112 (26 binary, 0 integer, 0 implicit integer, 86 continuous)
\   Constraints      : 123
Minimize
 Obj: +1 x1 +0.6 x3 +1.1 x4 +0.75 x5 +1 x6 +0.8 x7 +1 x8 +1 x9 +1 x11 +1.5 x13 +1.2 x15
Subject to
 c1: -1 x1 -0.6 x3 -1.1 x4 -0.75 x5 -1 x6 -0.8 x7 -1 x8 -1 x9 -1 x11 -1.5 x13 -1.2 x15 <= +0
 c2: +1 x1 +0.6 x3 +1.1 x4 +0.75 x5 +1 x6 +0.8 x7 +1 x8 +1 x9 +1 x11 +1.5 x13 +1.2 x15 <= +4
 c4: +1 x16 -1 x18 +1 x30 -1 x47 <= +0
 c5: -1 x16 +0.4 x28 +1 x29 -1 x55 <= +0
 c6: +1 x21 +1 x27 -1 x57 <= +0
 c7: +1 x23 +1 x31 <= +0
 c8: +1 x27 -1 x33 <= +0
 c9: +4.5 x27 -1 x43 <= +0
 c10: +1 x24 -100 x27 <= +0
 c11: +1 x25 -100 x27 <= +0
 c12: -100 x27 +1 x32 <= +0
 c13: -100 x27 +1 x33 <= +0
 c14: -100 x27 +1 x34 <= +0
 c15: -1 x24 -100 x27 <= +0
 c16: -100 x27 +1 x35 <= +0
 c17: -100 x27 +1 x36 <= +0
 c18: -1 x25 -100 x27 <= +0
 c19: -100 x27 +1 x37 <= +0
 c20: -100 x27 +1 x38 <= +0
 c21: -10 x27 +1 x39 <= +0
 c22: -100 x27 +1 x40 <= +0
 c23: -100 x27 +1 x41 <= +0
 c24: -100 x27 +1 x42 <= +0
 c25: -0.1 x29 -1 x30 -4.5 x31 -1 x41 +100 x44 +100 x45 +100 x46 +100 x47 +100 x48 +100 x49 +100 x50 +100 x51
  +100 x52 +100 x53 +100 x54 +10 x55 +100 x56 +100 x57 +100 x58 <= -1
 c26: +1 x23 <= +0
 c27: +1 x59 +9 x1 <= +9
 c28: +1 x61 -4.9 x3 <= +0
 c29: +1 x62 +10 x4 <= +10
 c30: +1 x63 +10 x5 <= +10
 c31: +1 x64 -10 x6 <= +0
 c32: +1 x65 +9 x7 <= +9
 c33: +1 x66 +9 x8 <= +9
 c34: +1 x67 +5 x9 <= +5
 c35: +1 x69 +9 x11 <= +9
 c36: +1 x71 +9.8 x13 <= +9.8
 c37: -1 x62 +4.9 x4 <= +4.9
 c38: -1 x65 +10 x7 <= +10
 c39: -1 x73 +5.5 x15 <= +5.5
 c40: +1 x32 +1 x33 +1 x34 +1 x37 -1 x39 = +0
 c41: -1 x25 -1 x32 +1 x36 +1 x38 = +0
 c42: -1 x33 +1 x34 +1 x35 +1 x36 +1 x38 = +0
 c43: +1 x24 -1 x34 +1 x35 = +0
 c44: +1 x25 -1 x36 -1 x37 +1 x40 = +0
 c45: -1 x35 -1 x36 -1 x38 +1 x41 = +0
 c46: -1 x24 -1 x34 -1 x35 -1 x38 +1 x42 = +0
 c47: +1 x26 -1 x36 +1 x43 = +0
 c48: -1 x59 -1 x60 -1 x61 -1 x66 +1 x68 = +0
 c49: +1 x59 -1 x64 -1 x65 -1 x67 = +0
 c50: +1 x60 -1 x61 -1 x63 -1 x64 -1 x67 = +0
 c51: +1 x61 +1 x62 -1 x63 = +0
 c52: +1 x64 +1 x65 +1 x66 -1 x69 = +0
 c53: +1 x63 +1 x64 +1 x67 -1 x70 = +0
 c54: +1 x61 -1 x62 +1 x63 +1 x67 -1 x71 = +0
 c55: +1 x64 -1 x72 +1 x73 = +0
constraint handler <xor> cannot print requested format
\   [xor] <XORcons>: xor(<x1>[B],<x74>[B]) = 1;
 IndicatorCons: x74 = 1 ->  +1 x16 -1 x17 -1 x46 <= +0
 IndicatorCons: x3 = 1 ->  +1 x16 +1 x18 -1 x19 -1 x22 -1 x48 <= +0
constraint handler <xor> cannot print requested format
\   [xor] <XORcons>: xor(<x5>[B],<x77>[B]) = 1;
 IndicatorCons: x77 = 1 ->  +1 x18 +1 x19 -1 x21 -1 x22 -1 x50 <= +0
 IndicatorCons: x6 = 1 ->  +1 x17 +1 x18 -1 x20 -1 x21 -1 x23 -1 x51 <= +0
constraint handler <xor> cannot print requested format
\   [xor] <XORcons>: xor(<x8>[B],<x80>[B]) = 1;
 IndicatorCons: x80 = 1 ->  +1 x16 -1 x20 -1 x53 <= +0
constraint handler <xor> cannot print requested format
\   [xor] <XORcons>: xor(<x9>[B],<x82>[B]) = 1;
 IndicatorCons: x82 = 1 ->  +1 x17 +1 x18 -1 x21 -1 x22 -1 x54 <= +0
constraint handler <xor> cannot print requested format
\   [xor] <XORcons>: xor(<x11>[B],<x84>[B]) = 1;
 IndicatorCons: x84 = 1 ->  +1 x20 -1 x28 -1 x56 <= +0
constraint handler <xor> cannot print requested format
\   [xor] <XORcons>: xor(<x13>[B],<x86>[B]) = 1;
 IndicatorCons: x86 = 1 ->  +1 x22 -1 x58 <= +0
constraint handler <xor> cannot print requested format
\   [xor] <XORcons>: xor(<x15>[B],<x88>[B]) = 1;
 IndicatorCons: x88 = 1 ->  -1 x23 <= +0
 IndicatorCons: x1 = 1 ->  +1 x32 <= +0
constraint handler <xor> cannot print requested format
\   [xor] <XORcons>: xor(<x3>[B],<x91>[B]) = 1;
 IndicatorCons: x91 = 1 ->  +1 x34 <= +0
 IndicatorCons: x5 = 1 ->  +1 x35 <= +0
constraint handler <xor> cannot print requested format
\   [xor] <XORcons>: xor(<x6>[B],<x94>[B]) = 1;
 IndicatorCons: x94 = 1 ->  +1 x36 <= +0
 IndicatorCons: x8 = 1 ->  +1 x37 <= +0
 IndicatorCons: x9 = 1 ->  +1 x38 <= +0
 IndicatorCons: x11 = 1 ->  +1 x40 <= +0
 IndicatorCons: x13 = 1 ->  +1 x42 <= +0
 IndicatorCons: x15 = 1 ->  +1 x73 <= +0
constraint handler <xor> cannot print requested format
\   [xor] <XORcons>: xor(<x4>[B],<x101>[B]) = 1;
 IndicatorCons: x101 = 1 ->  +1 x19 -1 x22 -1 x44 +1 x49 <= +0
 IndicatorCons: x101 = 1 ->  -1 x19 +1 x22 +1 x44 -1 x49 <= +0
constraint handler <xor> cannot print requested format
\   [xor] <XORcons>: xor(<x7>[B],<x104>[B]) = 1;
 IndicatorCons: x104 = 1 ->  -1 x17 +1 x20 -1 x45 +1 x52 <= +0
 IndicatorCons: x104 = 1 ->  +1 x17 -1 x20 +1 x45 -1 x52 <= +0
 IndicatorCons: x4 = 1 ->  +1 x24 <= +0
 IndicatorCons: x4 = 1 ->  -1 x24 <= +0
 IndicatorCons: x7 = 1 ->  +1 x25 <= +0
 IndicatorCons: x7 = 1 ->  -1 x25 <= +0
 IndicatorCons: x15 = 1 ->  +1 x26 <= +0
 IndicatorCons: x15 = 1 ->  -1 x26 <= +0
Bounds
 0 <= x1 <= 1
 0 <= x2 <= 0
 0 <= x3 <= 1
 0 <= x4 <= 1
 0 <= x5 <= 1
 0 <= x6 <= 1
 0 <= x7 <= 1
 0 <= x8 <= 1
 0 <= x9 <= 1
 0 <= x10 <= 0
 0 <= x11 <= 1
 0 <= x12 <= 0
 0 <= x13 <= 1
 0 <= x14 <= 0
 0 <= x15 <= 1
 0 <= x74 <= 1
 0 <= x77 <= 1
 0 <= x80 <= 1
 0 <= x82 <= 1
 0 <= x84 <= 1
 0 <= x86 <= 1
 0 <= x88 <= 1
 0 <= x91 <= 1
 0 <= x94 <= 1
 0 <= x101 <= 1
 0 <= x104 <= 1
 x27 free
 0 <= x59 <= 100
 1 <= x60 <= 100
 0 <= x61 <= 100
 -100 <= x62 <= 100
 0 <= x63 <= 100
 0 <= x64 <= 100
 -100 <= x65 <= 100
 0 <= x66 <= 100
 0 <= x67 <= 100
 0 <= x68 <= 10
 0 <= x69 <= 100
 0.2 <= x70 <= 100
 0 <= x71 <= 100
 4.5 <= x72
 x73 free
 x16 free
 x17 free
 x18 free
 x19 free
 x20 free
 x21 free
 x22 free
 x23 free
 x24 free
 x25 free
 x26 free
Binaries
 x1 x2 x3 x4 x5 x6 x7 x8 x9 x10 x11 x12 x13 x14 x15 x74 x77 x80 x82 x84 x86 x88 x91 x94 x101 x104
End

Since scipopt/PySCIPOpt#486 was closed but never solved I am making the same issue here.

is there a way to check what conditions are failing when the optimization result is infeasible or get the latest (infeasible) solution from the solver?

Hi all. Several months ago I opened an issue on the PySCIPOpt repo containing an example where PySCIPOpt 4.2 (running SCIP 8) incorrectly claimed that a small SOCP was infeasible. Since the issue has seen no activity over there and it probably belongs here, I'm posting just to make sure the SCIP devs are aware.

The relevant issue is: scipopt/PySCIPOpt#583.

Ping @BrannonKing, since he might be interested in this getting resolved.

DISCLAIMER: All details (and a minimal reproducible example) are in Mizux/scip-multithread#2

It seems, on GitHub linux hosted worker, the method SCIPsyncstoreGetWinner() will return -1 nearly each time
Open Questions:
* Why code didn't check the index value or retcode before using the return value ?
* Why we have so many -1 return by SCIPsyncstoreGetWinner() ?
* Why syncstore->lastsync is empty while SCIPtpiCollectJobs(jobid) seems to have correctly collected all results ?

ref: Mizux/scip-multithread#2 (comment)

Hi, I found bug on SCIP concurrentopt function. I compiled IPOPT with HSL libraries contains HSL_MA97 which use OpenMP for parallel computation. I configure SCIP to use HSL_MA97 via command "set nlpi ipopt linear_solver ma97". When I try to start concurrentopt fails. I think, this problem hard to fix but some explanation can be added for wrong settings. Thanks for for your hard work.

I have been experimenting with special ordered sets of type 2 and noticed that I have been getting different optimal solutions based on the weights and their order.

The following SOS2 constraint (in .lp format) is recognised and solved correctly (objective = -2):

SOS

x10: S2::
  x4:1
  x5:2
  x6:3

The following SOS2 constraint (in .lp format) is recognised but not solved correctly (objective = 3):

SOS

x10: S2::
  x4:25
  x5:18
  x6:22

The correct solution is only produced when the weights are in monotonically ascending or descending order. I also tried to swap the order of the variables but it did not produce the right solution.

I am enclosing the aforementioned problems:
sos2.zip

I found the same behaviour with CPLEX but not with CBC (correct result with both files). Is this a bug? Can somebody explain why this happens? Does the format require us to write the constraint with the variables and the weights in a specific order?

EDIT: Added information about the results with CBC.

Good afternoon.

I have created an example model where SCIP finds an optimal solution, but if certain constraints are removed, SCIP claims the model is infeasible.

With these constraints (plus some bound constraints):

We get this optimal solution:

And simply deleting the temperature constraints:

We get an infeasible model:

Maybe I am not thinking clearly, but it seems that this should not happen. You can see the code here: incorrect_infeasibility.zip.

Well I couldn't install ipopt as Android lacks fortran compilers & workarounds are beyond me. All were installed in /usr/local
What i can install successfully are papilo. A bug is resolved as well

git clone https://github.com/scipopt/papilo.git
cd papilo 
https://github.com/scipopt/papilo/issues/20
export LDFLAGS="-llog" && cmake -DCMAKE_INSTALL_PREFIX=$PREFIX/local .. && make -j8 && make install

soplex was as well installed

git clone https://github.com/scipopt/soplex.git
mkdir build
cd build
cmake -DCMAKE_INSTALL_PREFIX=$PREFIX/local -DPAPILO=on ..

zimpl was as well installed (very good small language). Its source was in the scioptsuite I couldn't find its separate git. On Android will throw error so link libm.so as following

cd scipoptsuite-8.0.1/zimpl/build
ln -s /apex/com.android.runtime/lib64/bionic/libm.so $PREFIX/lib/
cmake -DCMAKE_INSTALL_PREFIX=$PREFIX/local  .. && make -j8 && make install

Finally build scip (I didnt use scioptsuite tar ball except for zimpl)

cd scip-8.0.1
mkdir build && cd build
cmake -DCMAKE_INSTALL_PREFIX=$PREFIX/local -DIPOPT=off  ..
make -j8 && make install

Further notes while configuring scip, I had COIN-OR cpl installed in my system but still following gets reported, the documentation doesnt refer how to force-enable it -- Support CLP: OFF

scip -v
SCIP version 8.0.1 [precision: 8 byte] [memory: block] [mode: debug] [LP solver: Soplex 6.0.1.3] [GitHash: c84ee4283e]
Copyright (C) 2002-2022 Konrad-Zuse-Zentrum fuer Informationstechnik Berlin (ZIB)

External libraries:
  Readline 8.1         GNU library for command line editing (gnu.org/s/readline)
  Soplex 6.0.1.3       Linear Programming Solver developed at Zuse Institute Berlin (soplex.zib.de) [GitHash: 713be0fe]
  CppAD 20180000.0     Algorithmic Differentiation of C++ algorithms developed by B. Bell (github.com/coin-or/CppAD)
  ZLIB 1.2.12          General purpose compression library by J. Gailly and M. Adler (zlib.net)
  GMP 6.2.1            GNU Multiple Precision Arithmetic Library developed by T. Granlund (gmplib.org)
  ZIMPL 3.5.2          Zuse Institute Mathematical Programming Language developed by T. Koch (zimpl.zib.de)
  AMPL/MP 4e2d45c4     AMPL .nl file reader library (github.com/ampl/mp)
  PaPILO 2.1.1         parallel presolve for integer and linear optimization (github.com/scipopt/papilo) [GitHash: dea16d4]
  bliss 0.77           Computing Graph Automorphism Groups by T. Junttila and P. Kaski (www.tcs.hut.fi/Software/bliss/)

Compiler: clang 14.0.6

Build options:
 ARCH=aarch64
 OSTYPE=Android-4.19.113-24856341
 COMP=Clang 14.0.6
 BUILD=RelWithDebInfo
 DEBUGSOL=OFF
 EXPRINT=cppad
 SYM=bliss
 GMP=ON
 IPOPT=off
 WORHP=OFF
 LPS=spx
 LPSCHECK=OFF
 NOBLKBUFMEM=OFF
 NOBLKMEM=OFF
 NOBUFMEM=OFF
 THREADSAFE=ON
 READLINE=ON
 SANITIZE_ADDRESS=OFF
 SANITIZE_MEMORY=OFF
 SANITIZE_UNDEFINED=OFF
 SANITIZE_THREAD=OFF
 SHARED=ON
 VERSION=8.0.1.0
 API_VERSION=104
 ZIMPL=ON
 ZLIB=ON

/usr/local/bin/ld: ../bin/scip: hidden symbol `xlp_conname_exists' in CMakeFiles/scip.dir/scip/reader_zpl.c.o is referenced by DSO
/usr/local/bin/ld: final link failed: bad value
c++: error: linker command failed with exit code 1 (use -v to see invocation)
*** [bin/scip] Error code 1

It appears that the cause is that xlp_conname_exists is defined in both SCIP and ZIMPL projects.

OS: FreeBSD 13
clang-11

When trying to compile SCIP from source, the build fails with

error: cannot convert ‘void(void*, unsigned int, const unsigned int*)’ to ‘const std::function<void(unsigned int, const unsigned int*)>&

in

I looked up the reference, seems like Bliss has changed the signature (user_param is no longer accepted as a param), Is SCIP using a forked version of the API?

I was able to surpass the error by rewriting the blisshook to

    auto blisshook = [&data](
      unsigned int          n,                  /**< size of aut vector */
      const unsigned int*   aut                 /**< automorphism */
      )
    {
      assert( aut != NULL );

      assert( data.scip != NULL );
      assert( data.npermvars < (int) n );
      assert( data.maxgenerators >= 0);

      /* make sure we do not generate more that maxgenerators many permutations, if the limit in bliss is not available */
      if ( data.maxgenerators != 0 && data.nperms >= data.maxgenerators )
          return;

      /* copy first part of automorphism */
      bool isIdentity = true;
      int* p = 0;
      if ( SCIPallocBlockMemoryArray(data.scip, &p, data.npermvars) != SCIP_OKAY )
          return;

      for (int j = 0; j < data.npermvars; ++j)
      {
          /* convert index of variable-level 0-nodes to variable indices */
          p[j] = (int) aut[j];
          if ( p[j] != j )
            isIdentity = false;
      }

      /* ignore trivial generators, i.e. generators that only permute the constraints */
      if ( isIdentity )
      {
          SCIPfreeBlockMemoryArray(data.scip, &p, data.npermvars);
          return;
      }

      /* check whether we should allocate space for perms */
      if ( data.nmaxperms <= 0 )
      {
          if ( data.maxgenerators == 0 )
            data.nmaxperms = 100;   /* seems to cover many cases */
          else
            data.nmaxperms = data.maxgenerators;

          if ( SCIPallocBlockMemoryArray(data.scip, &data.perms, data.nmaxperms) != SCIP_OKAY )
            return;
      }
      else if ( data.nperms >= data.nmaxperms )    /* check whether we need to resize */
      {
          int newsize = SCIPcalcMemGrowSize(data.scip, data.nperms + 1);
          assert( newsize >= data.nperms );
          assert( data.maxgenerators == 0 );

          if ( SCIPreallocBlockMemoryArray(data.scip, &data.perms, data.nmaxperms, newsize) != SCIP_OKAY )
            return;

          data.nmaxperms = newsize;
      }

      data.perms[data.nperms++] = p;
    };

and the call to

   G.find_automorphisms(stats, blisshook);

It is now working as expected, if you think that's a correct fix, I can prepare a patch :).

Thanks.

I am trying to understand

1. the right way of using SCIPgetDualsolLinear
2. the difference between SCIPgetDualsolLinear and SCIPgetDualSolVal

Looking at their documentation, both should do more or less the same

• SCIPgetDualsolLinear: https://www.scipopt.org/doc/html/group__CONSHDLRS.php#ga0bd06cd82e491728d839582c0520c7bd
• SCIPgetDualSolVal: https://www.scipopt.org/doc/html/group__PublicSolutionMethods.php#ga499a5c0adebcc321cce0d47bc6313305

I originally opened a similar issue at PySCIPOpt (issue) they sent me here so I tried to recreate the issue using the C-API:

What did I do

When trying to get the optimal dual values of an LP solution, only SCIPgetDualSolVal seems to return the correct value:

#include <stdio.h>
#include <stdbool.h>

#include "scip/scip.h"
#include <scip/scipdefplugins.h>

int main() {
    // Setup
    SCIP* scip;
    SCIP_CALL_ABORT(SCIPcreate(&scip));
    SCIP_CALL_ABORT(SCIPincludeDefaultPlugins(scip));

    // Turn off features that seem problematic in conjunction with duals:
    // https://www.solveforum.com/forums/threads/solved-how-to-completeley-disable-presolve-in-scip.2697850/
    // https://github.com/scipopt/PySCIPOpt/issues/136
    SCIP_CALL_ABORT(SCIPsetPresolving(scip, SCIP_PARAMSETTING_OFF, true));
    SCIP_CALL_ABORT(SCIPsetHeuristics(scip, SCIP_PARAMSETTING_OFF, true));
    SCIP_CALL_ABORT(SCIPsetIntParam(scip, "propagating/maxrounds", 0));
        
    SCIP_CALL_ABORT(SCIPcreateProb(scip, "primal", NULL, NULL,
                                 NULL, NULL, NULL, NULL, NULL));
    SCIP_CALL_ABORT(SCIPsetObjsense(scip, SCIP_OBJSENSE_MAXIMIZE));

    // Variables: x,y positive reals
    SCIP_VAR* x;
    SCIP_CALL_ABORT(SCIPcreateVar(scip, &x, "x", 0.0, SCIPinfinity(scip), 1.0,
                                  SCIP_VARTYPE_CONTINUOUS, TRUE, FALSE,
                                  NULL, NULL, NULL, NULL, NULL));
    SCIP_CALL_ABORT(SCIPaddVar(scip, x));
    
    SCIP_VAR* y;
    SCIP_CALL_ABORT(SCIPcreateVar(scip, &y, "y", 0.0, SCIPinfinity(scip), 1.0,
                                  SCIP_VARTYPE_CONTINUOUS, TRUE, FALSE,
                                  NULL, NULL, NULL, NULL, NULL));
    SCIP_CALL_ABORT(SCIPaddVar(scip, y));

    // Constraints
    SCIP_CONS* c1;
    SCIP_VAR* vars[2] = {x, y};
    double coeffs1 [2] = {1.0, 2.0};
    SCIP_CALL_ABORT(SCIPcreateConsLinear(scip, &c1, "c1",
                                         2, vars, coeffs1, 21.0, 21.0, TRUE,
                                         TRUE, TRUE, TRUE, TRUE, FALSE,
                                         FALSE, FALSE, FALSE, FALSE));
    SCIP_CALL_ABORT(SCIPaddCons(scip, c1));
    
    SCIP_CONS* c2;
    double coeffs2 [2] = {2.0, 1.0};
    SCIP_CALL_ABORT(SCIPcreateConsLinear(scip, &c2, "c2",
                                         2, vars, coeffs2, 24.0, 24.0, TRUE,
                                         TRUE, TRUE, TRUE, TRUE, FALSE,
                                         FALSE, FALSE, FALSE, FALSE));
    SCIP_CALL_ABORT(SCIPaddCons(scip, c2));

    // Solution
    SCIP_CALL_ABORT(SCIPsolve(scip));
    SCIP_SOL* sol = SCIPgetBestSol(scip);
    if (sol == NULL){
        printf("No solution found\n");
    }
    else {
    
        double x_val = SCIPgetSolVal(scip, sol, x);
        double y_val = SCIPgetSolVal(scip, sol, y);
        double c1_dual = SCIPgetDualsolLinear(scip, c1);
        double c2_dual = SCIPgetDualsolLinear(scip, c2);
        double c1_dual2;
        double c2_dual2;
        SCIP_CALL_ABORT(SCIPgetDualSolVal(scip, c1, &c1_dual2, NULL));
        SCIP_CALL_ABORT(SCIPgetDualSolVal(scip, c2, &c2_dual2, NULL));
 
        printf("Solution: x = %f, y = %f\n", x_val, y_val);
        printf("getDualsolLinear: c1_dual = %f, c2_dual = %f\n", c1_dual, c2_dual);
        printf("getDualSolVal: c1_dual = %f, c2_dual = %f\n", c1_dual2, c2_dual2);
    }
    
    // Cleanup
    SCIP_CALL_ABORT(SCIPreleaseVar(scip, &x));
    SCIP_CALL_ABORT(SCIPreleaseVar(scip, &y));
    SCIP_CALL_ABORT(SCIPreleaseCons(scip, &c1));
    SCIP_CALL_ABORT(SCIPreleaseCons(scip, &c2));
    SCIP_CALL_ABORT(SCIPfree(&scip));

    
    return 0;
}

output:

Solution: x = 9.000000, y = 6.000000
getDualsolLinear: c1_dual = 0.000000, c2_dual = 0.000000
getDualSolVal: c1_dual = 0.333333, c2_dual = 0.333333

The optimal dual values of constraints c1 and c2 are both 1/3, so only getDualSolVal returns the right value but getDualsolLinear doesn't.

Questions

• Is this the expected behaviour from getDualsolLinear?
• If not, am I using it incorrectly?
• What is the difference in usage and in result between getDualsolLinear and getDualSolVal?

My setup

I'm using SCIP 8.0.3 installed using conda on a Linux machine.
More details:

$ scip --version
SCIP version 8.0.3 [precision: 8 byte] [memory: block] [mode: optimized] [LP solver: Soplex 6.0.3] [GitHash: 62fab8a2e3]
Copyright (C) 2002-2022 Konrad-Zuse-Zentrum fuer Informationstechnik Berlin (ZIB)

External libraries: 
  Soplex 6.0.3         Linear Programming Solver developed at Zuse Institute Berlin (soplex.zib.de) [GitHash: f900e3d0]
  CppAD 20180000.0     Algorithmic Differentiation of C++ algorithms developed by B. Bell (github.com/coin-or/CppAD)
  ZLIB 1.2.13          General purpose compression library by J. Gailly and M. Adler (zlib.net)
  GMP 6.2.1            GNU Multiple Precision Arithmetic Library developed by T. Granlund (gmplib.org)
  ZIMPL 3.5.3          Zuse Institute Mathematical Programming Language developed by T. Koch (zimpl.zib.de)
  AMPL/MP 4e2d45c4     AMPL .nl file reader library (github.com/ampl/mp)
  PaPILO 2.1.2         parallel presolve for integer and linear optimization (github.com/scipopt/papilo) [GitHash: 2fe2543]
  bliss 0.77           Computing Graph Automorphism Groups by T. Junttila and P. Kaski (www.tcs.hut.fi/Software/bliss/)
  Ipopt 3.14.12        Interior Point Optimizer developed by A. Waechter et.al. (github.com/coin-or/Ipopt)

Compiler: gcc 12.2.0

Build options:
 ARCH=x86_64
 OSTYPE=Linux-5.15.0-1037-azure
 COMP=GNU 12.2.0
 BUILD=Release
 DEBUGSOL=OFF
 EXPRINT=cppad
 SYM=bliss
 GMP=ON
 IPOPT=ON
 WORHP=OFF
 LPS=spx
 LPSCHECK=OFF
 NOBLKBUFMEM=OFF
 NOBLKMEM=OFF
 NOBUFMEM=OFF
 THREADSAFE=ON;FORCE
 READLINE=OFF
 SANITIZE_ADDRESS=OFF
 SANITIZE_MEMORY=OFF
 SANITIZE_UNDEFINED=OFF
 SANITIZE_THREAD=OFF
 SHARED=ON
 VERSION=8.0.3.0
 API_VERSION=104
 ZIMPL=ON
 ZLIB=ON

I am very excited to use SCIP v8.0.3 under the Apache 2 license in a commercial product. When do you expect to schedule 8.0.3's release? I am asking so that I can plan around it in upcoming releases of my software.

If this is a question better directed to [email protected], please let me know.

to reflect the new license and to allow automatic downloads

I downloaded last version of SCIP from git repo. I compiled without any error. But I get this error massage when try to install with "sudo make install":

fatal: unsafe repository ('/home/radxa/Downloads/scip' is owned by someone else)
To add an exception for this directory, call:

        git config --global --add safe.directory /home/radxa/Downloads/scip
CMake Error at scip_update_githash.cmake:12 (string):
  string sub-command REGEX, mode REPLACE needs at least 6 arguments total to
  command.


make[2]: *** [CMakeFiles/scip_update_githash.dir/build.make:70: CMakeFiles/scip_update_githash] Error 1
make[1]: *** [CMakeFiles/Makefile2:719: CMakeFiles/scip_update_githash.dir/all] Error 2
make: *** [Makefile:166: all] Error 2

I tried to add safe directory but nothing changed. I'm working on ARM architecture Radxa Zero.(cmake 3.23.1, Make 4.3)

Add a github action to build the SCIP Optimization Suite for different operating systems with the latest version of SCIP. It should be triggered when a tag is added.

Hello， I use or-tools with scip to solve my case. In one case, I get the message "violation: right hand side is violated by 1049.999",
it seems this is a numerical problem. I wonder how to resolve this problem.

[2023-05-30 19:57:41,156] [DEBUG] autorosterplant_model.py [line:545] [autorosterplant_model] - begin solve level 1
[linear] <auto_c_000000152>: +10<underSkillLevel_891_3_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_6189_2_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_61812_4_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_61814_3_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_891_4_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_61811_3_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_999_3_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_891_1_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_61814_2_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_6189_3_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3)
+10<underSkillLevel_6186_1_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_61811_4_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_999_4_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_61815_3_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_61810_3_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_61815_1_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_61815_2_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_61810_1_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_61814_4_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_6186_4_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_6189_4_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_6186_3_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_61810_4_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_61812_3_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_6186_2_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_891_2_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_999_2_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_61812_2_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_61812_1_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_999_1_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_6189_1_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_61810_2_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_61811_1_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_61811_2_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) +10<underSkillLevel_61815_4_3a0682b5-f814-46c3-8614-922161a72876_569>[I] (+3) <= 0.001;
;
violation: right hand side is violated by 1049.999
1/3 feasible solution given by solution candidate storage, new primal bound 4.800000e+04

presolving:
(round 1, fast) 92 del vars, 143 del conss, 0 add conss, 89 chg bounds, 32 chg sides, 0 chg coeffs, 0 upgd conss, 0 impls, 0 clqs
(0.0s) probing cycle finished: starting next cycle
Deactivated symmetry handling methods, since SCIP was built without symmetry detector (SYM=none).
presolving (2 rounds: 2 fast, 1 medium, 1 exhaustive):
92 deleted vars, 157 deleted constraints, 0 added constraints, 89 tightened bounds, 0 added holes, 32 changed sides, 0 changed coefficients
0 implications, 0 cliques
presolved problem has 17 variables (17 bin, 0 int, 0 impl, 0 cont) and 0 constraints
transformed objective value is always integral (scale: 1000)
Presolving Time: 0.00
transformed 1/1 original solutions to the transformed problem space

time | node | left |LP iter|LP it/n|mem/heur|mdpt |vars |cons |rows |cuts |sepa|confs|strbr| dualbound | primalbound | gap | compl.
t 0.0s| 1 | 0 | 0 | - | trivial| 0 | 17 | 0 | 0 | 0 | 0 | 0 | 0 | 3.100000e+04 | 3.100000e+04 | 0.00%| unknown

SCIP Status : problem is solved [optimal solution found]
Solving Time (sec) : 0.00
Solving Nodes : 1
Primal Bound : +3.10000000000000e+04 (2 solutions)
Dual Bound : +3.10000000000000e+04
Gap : 0.00 %
##################################

There are a lot of errors like those:

I have a MILP problem that is having trouble running through SCIP with pyscipopt. Two specific variables would occasionally cause an error. The error message is listed below:

[tree.c:1875] ERROR: cannot change bounds of multi-aggregated variable <t_x3377>
[tree.c:2098] ERROR: Error <-9> in function call
[scip_var.c:5388] ERROR: Error <-9> in function call
[presol_implics.c:278] ERROR: Error <-9> in function call
[presol.c:466] ERROR: Error <-9> in function call
[scip_solve.c:1081] ERROR: Error <-9> in function call
[scip_solve.c:1208] ERROR: Error <-9> in function call
[scip_solve.c:1374] ERROR: Error <-9> in function call
[scip_solve.c:2484] ERROR: Error <-9> in function call
[scip_solve.c:2722] ERROR: Error <-9> in function call
[dialog_default.c:2183] ERROR: Error <-9> in function call
[dialog.c:942] ERROR: Error <-9> in function call
[dialog.c:393] ERROR: Error <-9> in function call
[scip_dialog.c:243] ERROR: Error <-9> in function call
[scipshell.c:479] ERROR: Error <-9> in function call
[scipshell.c:533] ERROR: Error <-9> in function call
SCIP Error (-9): method cannot be called with this type of data

The attachment contains my test file. I saved the model in .lp and .cip formats before the error occurred.
test_lp_transform.cip is a file that tranfrom from test.lp. I figured out that the difference between test.cip and test_lp_transform.cip is the order of the variable, which would cause a different presolving result.

test.cip can reproduce the error in scip.
test.lp can be successfully optimized in scip.
test_lp_transform.cip can be successfully optimized in scip.

test.zip

Hi, I need to solve numerically difficult LP problems, and would like to use SoPlex as an exact LP solver from SCIP. In order to use SoPlex in exact mode, I need to set some parameters(e.g. setting both feastol and opttol to $0$ ) according to https://soplex.zib.de/doc/html/EXACT.php

However, I can't find a way to set the params in SCIP. In https://scipopt.org/doc/html/PARAMETERS.php, I can only find numerics/feastol and the minimal allowed value is $1e-17$.

Is there a way to set the SoPlex parameters through SCIP to make it solve in exact mode? Thank you for any help

I've just tried to install SCIPOptSuite-8.0.3-Linux-debian.deb on a Debian machine, and I'm getting conflicts with the bliss package as both scipoptsuite and bliss want to install /usr/bin/bliss. I tried to find out how the debian package is actually built, but couldn't find any specific build script for creating the Debian package.

I do realise that SCIPOptSuite needs bliss 0.77, while debian stable (bullseye) and testing (bookworm) both only have bliss 0.73 available, so making SCIPOptSuite installable on debian stable is going to need some sort of internal bliss build (and possibly the same for other libraries), but would it be possible to create debian packages that won't have file collisions with other debian packages? I'm happy to attempt to make a build script for this if there is interest.

TLDR: It seems the SCIP source depends on M_PI which is a GNU extension, i.e. compiling using -std=c99 won't work.

Protocol

If here:

set(CMAKE_C_EXTENSIONS OFF)

Then CMake will generate compile line using -std=c99 instead of the "default" -std=gnu99

ref: https://cmake.org/cmake/help/latest/variable/CMAKE_CXX_EXTENSIONS.html
note: You can also pass it on CMake configure line or could be given by a super project integrating SCIP from sources...
note2: Usually CMake default enable extensions seems to have change 17months ago see
Kitware/CMake@f034b0f

Observed

note: I'm doing some integration tests of multithread SCIP so technically I building SCIP using through FetchContent()
full project here: https://github.com/Mizux/scip-multithread

cmake --build build -v
...
[ 17%] Building C object _deps/scip-build/src/CMakeFiles/libscip.dir/scip/cons_soc.c.o
cd /home/mizux/dev/scip-multithread/build/_deps/scip-build/src && /usr/bin/clang
 -I/home/mizux/dev/scip-multithread/build/_deps/scip-build
 -I/home/mizux/dev/scip-multithread/build/_deps/scip-src/src
 -I/home/mizux/dev/scip-multithread/build/_deps/zlib-build
 -I/home/mizux/dev/scip-multithread/build/_deps/zlib-src
 -fsanitize=thread -g -fPIC -fvisibility=hidden -std=c99 # SEE HERE the use of -std=c99
 -MD -MT
 _deps/scip-build/src/CMakeFiles/libscip.dir/scip/cons_soc.c.o
 -MF CMakeFiles/libscip.dir/scip/cons_soc.c.o.d
 -o CMakeFiles/libscip.dir/scip/cons_soc.c.o
 -c /home/mizux/dev/scip-multithread/build/_deps/scip-src/src/scip/cons_soc.c
/home/mizux/dev/scip-multithread/build/_deps/scip-src/src/scip/cons_soc.c:1996:10: error: use of undeclared identifier 'M_PI'
   val = M_PI;
         ^
/home/mizux/dev/scip-multithread/build/_deps/scip-src/src/scip/cons_soc.c:2238:13: error: use of undeclared identifier 'M_PI'
      val = M_PI / pow(2.0, (double) (i+1));
            ^
/home/mizux/dev/scip-multithread/build/_deps/scip-src/src/scip/cons_soc.c:2313:19: error: use of undeclared identifier 'M_PI'
   vals[0] = tan( M_PI / pow(2.0, (double) (N+1)) );
                  ^
3 errors generated.
make[2]: *** [_deps/scip-build/src/CMakeFiles/libscip.dir/build.make:776: _deps/scip-build/src/CMakeFiles/libscip.dir/scip/cons_soc.c.o] Error 1
make[2]: Leaving directory '/home/mizux/dev/scip-multithread/build'
make[1]: *** [CMakeFiles/Makefile2:1057: _deps/scip-build/src/CMakeFiles/libscip.dir/all] Error 2
make[1]: Leaving directory '/home/mizux/dev/scip-multithread/build'
make: *** [Makefile:166: all] Error 2

note: I tweaked the indent of the trace
fun fact: PI only officially exist since C++20 (https://en.cppreference.com/w/cpp/numeric/constants)

Proposal

If i were you:

1. I would be explicit, because in case of a super project build integrating scip with this option to OFF it will fail.
   Ie since it seems mandatory you should force it -> set(CMAKE_C_EXTENSIONS ON)
2. add a define in case...

   #ifndef M_PI
   #define M_PI 3.14159265358979323846
   #endif

Platform

FYI

%uname -a
Linux nuc10i7 5.13.5-arch1-1 #1 SMP PREEMPT Sun, 25 Jul 2021 18:02:58 +0000 x86_64 GNU/Linux
%gcc --version
gcc (GCC) 11.1.0
% clang --version
clang version 12.0.1
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin

I've been studying nlhdlr_quadratic.c to understand how to iterate the extreme rays when at an optimum of the LP relaxation. It's more complex than expected. (It might be less complex if the code for handling quadratics was not part of it.) Is it possible to expose some public methods for iterating the extreme rays of an optimal corner? This is surely a common need for modern cutting techniques, no?

In the meantime, can you give some guidance on iterating extreme rays of the corner in a custom separator for MILP problems?

I have 2 questions:

1. Is it possible to remove a node from the node pool during the solving process safely? I want to remove a subtree from the solving process.
2. If so, is it possible to do that in fscip? Since fscip is a parallel version of scip, should I use some mutex/lock to accomplish this?

Thanks.

Here are the input:

Hello!

I'm working with various models in the domain of Energy Markets. Some of my models are quite large (tens of millions of variables, millions of constraints) and I'm constantly looking for ways to improve the solving time. I would love to experiment with SCIP but I couldn't find a way to pass the entire problem to the solver with a single function call (well, 3-4 would be ok too but not millions ;)
I developed a generic solver interface for my kind of models, such that at the high level takes network objects (such as Supply/Transport/Demand nodes and Edges) and at the low level passes corresponding variables and constraints down to a solver in the form of ordered lower_bound/upper_bound/cost arrays for variables, and CSC matrix and bounds arrays for constraints.
So far, I managed to integrate my library with

1. Gurobi via GRBloadmodel
2. CBC via Cbc_loadProblem
3. HiGHS via Highs_passLp/Highs_passMip

I'm sure a similar method exists in Mosek but I haven't had a chance to integrate with it just yet.
These methods allow me to quickly integrate different solvers through thin driver libraries as my generic library outputs almost exactly what these methods accept. But I can't find any similar function in the C API of SCIP and the need to pass every variable and constraint with a function call holds me back.

I saw this struct_matrix.h in the docs but it seems this structure can only be read from the model once it is all set up and never used to actually create/load a problem.

I hope to be wrong, or let this be a feature request otherwise =)

Thank you!

I am trying to use SCIP to solve a quadratic optimization problem.
As a baseline I tried to install cvxpy and SCIP and solve the MQIP sample problem at https://www.cvxpy.org/examples/basic/mixed_integer_quadratic_program.html

However I get a SIGILL termination message. after the SCIP solver is invoked, not 100% sure this is on SCIP to blame.

scip -v output:

SCIP version 8.0.3 [precision: 8 byte] [memory: block] [mode: optimized] [LP solver: Soplex 6.0.3] [GitHash: 62fab8a2e3]
Copyright (C) 2002-2022 Konrad-Zuse-Zentrum fuer Informationstechnik Berlin (ZIB)

External libraries: 
  Readline 8.0         GNU library for command line editing (gnu.org/s/readline)
  Soplex 6.0.3         Linear Programming Solver developed at Zuse Institute Berlin (soplex.zib.de) [GitHash: f900e3d0]
  CppAD 20180000.0     Algorithmic Differentiation of C++ algorithms developed by B. Bell (github.com/coin-or/CppAD)
  ZLIB 1.2.11          General purpose compression library by J. Gailly and M. Adler (zlib.net)
  GMP 6.2.0            GNU Multiple Precision Arithmetic Library developed by T. Granlund (gmplib.org)
  AMPL/MP 4e2d45c4     AMPL .nl file reader library (github.com/ampl/mp)
  bliss 0.77           Computing Graph Automorphism Groups by T. Junttila and P. Kaski (www.tcs.hut.fi/Software/bliss/)

Compiler: gcc 9.4.0

Build options:
 ARCH=x86_64
 COMP=gnu
 DEBUGSOL=false
 EXPRINT=cppad
 GMP=true
 IPOPT=false
 IPOPTOPT=opt
 LPS=spx2
 LPSCHECK=false
 LPSOPT=opt
 NOBLKBUFMEM=false
 NOBLKMEM=false
 NOBUFMEM=false
 OPT=opt
 OSTYPE=linux
 THREADSAFE=true
 PAPILO=false
 READLINE=true
 SANITIZE=
 SHARED=false
 SYM=bliss
 USRARFLAGS=
 USRCFLAGS=
 USRCXXFLAGS=
 USRFLAGS=
 USRLDFLAGS=
 USROFLAGS=
 VERSION=8.0.3
 WORHP=false
 WORHPOPT=opt
 ZIMPL=false
 ZIMPLOPT=opt
 AMPL=true
 ZLIB=true

cat /proc/cpuinfo output:

Linux [REDACTED] 5.15.0-56-generic #62~20.04.1-Ubuntu SMP Tue Nov 22 21:24:20 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux

Attaching a zip containing the dump file

dump_file.zip

https://github.com/scipopt/scip/blob/master/src/scip/lp.c#L11711

I have been using SCIP through pyomo and through the command line and have recently come across a funny result: the solution appears to be calculated correctly, since pyomo stores the variables with the correct result, but the solution is not shown in the printout. I have tested this also in the command line and the result is the same.

The optimal solution is 2.9242718553e-04 (determined through the variables stored in pyomo and confirmed manually and via CPLEX) but SCIP prints that it is +0.00000000000000e+00 instead.

I am using debian bookworm and SCIP 8.0.3 but I had to handle some dependencies in unusual ways to install it.

I am attaching the problem so that this may be confirmed.
scip_problem.zip

Hi there,

I was wondering if there will be an arm64/aarch64 binary of SCIP. I have used SCIP across all different platform (Windows, Linux x86_64, arm32). But currently run into some problem on Ubuntu arm64 (on a Raspberry Pi 4B). I have tried the Raspberry Pi binary but apparently it needs some kernel support to run arm32 binary.

It will be great if you will release aarch64 binary in the future.

Thanks!

Hello,

I am looking for a way to get all rows including those that are not in the current LP. I know that SCIPgetLPRows() returns the rows in the current LP but I also need those that are not in the current LP. I did not see a function that does this, so I was wondering if there is another way to achieve this? Thanks!

Hello!

I came across a nasty issue when trying to solve a model from an LP file.

As far as I can tell, the SCIPOPT LP parser follows the LP specification of CPLEX:

• https://www.scipopt.org/doc-7.0.3/html/reader__lp_8h.php
• https://www.ibm.com/docs/en/icos/12.9.0?topic=cplex-lp-file-format-algebraic-representation

From testing, I do know (now) that CPLEX does not support constant values within the constraint expressions. The specification itself does not explicitly state this:

• "The constraints are entered in the same way as the objective function".
• Objective expressions support constants in the (objective-) expression

This is not the nicest definition, but something that can be worked with.

Problem description

If CPLEX is presented with an LP file that violates this rule, an error is raised:

invalid.lp

\none
Maximize
 var_x 
Subject To
 var_x - 1 = 0
Bounds
 1 <= var_x <= 1
Binary
 var_x
End

CPLEX output

CPLEX> read invalid.lp
CPLEX Error  1616: Line 5: Expected identifier, found '='.
No file read.
CPLEX>

If the same LP is given to SCIPOPT, it is read without error, and solved:
SCIPOPT output

SCIP> read C:\temp\scip\invalid.lp

read problem <C:\temp\scip\invalid.lp>
============

original problem has 1 variables (1 bin, 0 int, 0 impl, 0 cont) and 1 constraints
SCIP> optimize

presolving:
presolving (1 rounds: 1 fast, 0 medium, 0 exhaustive):
 1 deleted vars, 0 deleted constraints, 0 added constraints, 0 tightened bounds, 0 added holes, 0 changed sides, 0 changed coefficients
 0 implications, 0 cliques
presolving detected infeasibility
Presolving Time: 0.00

SCIP Status        : problem is solved [infeasible]
Solving Time (sec) : 0.00
Solving Nodes      : 0
Primal Bound       : -1.00000000000000e+20 (objective limit, 0 solutions)
Dual Bound         : +1.00000000000000e+20
Gap                : 0.00 %

SCIP simply omits the constant in the constraint expression, and solves the (inconsistent) problem. In this case, the model becomes infeasible by omitting the constant. However, with a slight adjustment to the LB of var_x, the model will become feasible and the result will deviate from the intended/expected solution:

feasible_invalid.lp

\none
Maximize
 var_x 
Subject To
 var_x - 1 = 0
Bounds
 0 <= var_x <= 1
Binary
 var_x
End

SCIP output (var_x LB = 0)

SCIP> read C:\temp\scip\feasible_invalid.lp

read problem <C:\temp\scip\feasible_invalid.lp>
============

original problem has 1 variables (1 bin, 0 int, 0 impl, 0 cont) and 1 constraints
SCIP> optimize

feasible solution found by trivial heuristic after 0.0 seconds, objective value 0.000000e+00
presolving:
presolving (1 rounds: 1 fast, 0 medium, 0 exhaustive):
 1 deleted vars, 0 deleted constraints, 0 added constraints, 1 tightened bounds, 0 added holes, 0 changed sides, 0 changed coefficients
 0 implications, 0 cliques
Presolving Time: 0.00

SCIP Status        : problem is solved [optimal solution found]
Solving Time (sec) : 0.00
Solving Nodes      : 0
Primal Bound       : +0.00000000000000e+00 (1 solutions)
Dual Bound         : +0.00000000000000e+00
Gap                : 0.00 %

If the same file is parsed + solved with, e.g., Gurobi (which supports constants in constraint expressions), the following output is produced:
Gurobi output

gurobi> m = read('feasible_invalid.lp')
Read LP format model from file feasible_invalid.lp
Reading time = 0.00 seconds
: 1 rows, 2 columns, 2 nonzeros
gurobi> m.optimize()
Gurobi Optimizer version 9.5.0 build v9.5.0rc5 (win64)
Thread count: 4 physical cores, 4 logical processors, using up to 4 threads
Optimize a model with 1 rows, 2 columns and 2 nonzeros
Model fingerprint: 0xf7308cbe
Variable types: 1 continuous, 1 integer (1 binary)
Coefficient statistics:
  Matrix range     [1e+00, 1e+00]
  Objective range  [1e+00, 1e+00]
  Bounds range     [1e+00, 1e+00]
  RHS range        [0e+00, 0e+00]
Found heuristic solution: objective -0.0000000
Presolve removed 1 rows and 2 columns
Presolve time: 0.00s
Presolve: All rows and columns removed

Explored 0 nodes (0 simplex iterations) in 0.00 seconds (0.00 work units)
Thread count was 1 (of 4 available processors)

Solution count 2: 1 -0

Optimal solution found (tolerance 1.00e-04)
Best objective 1.000000000000e+00, best bound 1.000000000000e+00, gap 0.0000%
gurobi>

Expected behavior

• Main priority
  • Given the current LP file format specification that SCIPOPT is following, I'd expect an error message when an invalid LP file is given. The silent fail might cause serious issues, since the resulting model might actually be feasible - but the solution differs from the "intended" model.
• Nice to have
  • Add support for constant values in constraints, similar to Gurobi's LP file format

I hope this is the correct address for reporting such an issue. If this is not the case, please let me know where I can/should submit it.

Best Regards,

Jannick

• scip-8.0.0

make install
output :

//usr/local/lib/libreadline.so.8: undefined reference to tgetstr' //usr/local/lib/libreadline.so.8: undefined reference to tputs'
//usr/local/lib/libreadline.so.8: undefined reference to BC' //usr/local/lib/libreadline.so.8: undefined reference to tgetent'
//usr/local/lib/libreadline.so.8: undefined reference to tgetflag' //usr/local/lib/libreadline.so.8: undefined reference to tgoto'
//usr/local/lib/libreadline.so.8: undefined reference to UP' //usr/local/lib/libreadline.so.8: undefined reference to tgetnum'
//usr/local/lib/libreadline.so.8: undefined reference to `PC'
collect2: error: ld returned 1 exit status
gcg/src/CMakeFiles/gcg.dir/build.make:2211: recipe for target 'bin/gcg' failed
make[2]: *** [bin/gcg] Error 1
CMakeFiles/Makefile2:2954: recipe for target 'gcg/src/CMakeFiles/gcg.dir/all' failed
make[1]: *** [gcg/src/CMakeFiles/gcg.dir/all] Error 2
Makefile:165: recipe for target 'all' failed
make: *** [all] Error 2

When trying to build SCIP in our Vagrant generic/FreeBSD13 box (note a FreeBSD VirtualBox img) we are facing some compilation issue...

Observed

here the relevant trace (please notice we are building SCIP using FetchContent from our or-tools CMake based build)

default: [ 48%] Building CXX object _deps/scip-build/src/CMakeFiles/libscip.dir/amplmp/src/os.cpp.o
    default: cd /usr/home/vagrant/project/build/_deps/scip-build/src && /usr/bin/c++  -I/usr/home/vagrant/project/build/_deps/scip-src/src/amplmp/include -I/usr/home/vagrant/project/build/_deps/scip-build -I/usr/home/vagrant/project/build/_deps/scip-src/src -I/usr/home/vagrant/project/build/_deps/zlib-build -I/usr/home/vagrant/project/build/_deps/zlib-src -O3 -DNDEBUG -fPIC -fvisibility=hidden -fvisibility-inlines-hidden -std=c++14 -MD -MT _deps/scip-build/src/CMakeFiles/libscip.dir/amplmp/src/os.cpp.o -MF CMakeFiles/libscip.dir/amplmp/src/os.cpp.o.d -o CMakeFiles/libscip.dir/amplmp/src/os.cpp.o -c /usr/home/vagrant/project/build/_deps/scip-src/src/amplmp/src/os.cpp
    default: /usr/home/vagrant/project/build/_deps/scip-src/src/amplmp/src/os.cpp:108:4: error: GetExecutablePath is not implemented for this system
    default: #  error GetExecutablePath is not implemented for this system
    default:    ^
    default: 1 error generated.
    default: *** Error code 1
    default: 
    default: Stop.
    default: make[2]: stopped in /usr/home/vagrant/project/build
    default: *** Error code 1
    default: 
    default: Stop.
    default: make[1]: stopped in /usr/home/vagrant/project/build
    default: *** Error code 1
    default: 
    default: Stop.
    default: make: stopped in /usr/home/vagrant/project/build
The SSH command responded with a non-zero exit status. Vagrant
assumes that this means the command failed. The output for this command
should be in the log above. Please read the output to determine what
went wrong.

ref: https://github.com/google/or-tools/runs/3672547012?check_suite_focus=true

Expected

Have support of FreeBSD so we can use it in OR-Tools or at least a dummy function instead of this error message breaking the build ;)
Also it seems that amplmp is only use to read some .nl file so it's sad to break the build for this "optional" feature...

Annexe

You can found our Vagrantfile here: https://github.com/google/or-tools/blob/master/cmake/vagrant/freebsd/cpp/Vagrantfile

note: I think it should be easy to adapt it to only build SCIP starting from your repo to get rid of or-tools shenanigan and/or add it as a CI job to this repo (if you are willing to use github action workflow) ;)

Hi everyone,
First of all, thank you for the work and the documentation you have done here, this is great.
When trying to compile the simple example (that I putted in a test file) :

#include <scip/scip.h>
#include <string>

TEST(solver, solver_SCIP_SOPLEX_initializarion)
{
    SCIP *scip = NULL;
    SCIP_CALL(SCIPcreate(&scip));                  // initialize SCIP
    SCIPinfoMessage(scip, NULL, "Hello world.\n"); // output greeting
    SCIP_CALL(SCIPfree(&scip));                    // free SCIP
    BMScheckEmptyMemory();
    ASSERT_EQ(1, 1);
}

I am faced to a message error:

In member function ‘virtual void solver_solver_SCIP_SOPLEX_initializarion_Test::TestBody()’:
**[...]**  error: return-statement with a value, in function returning ‘void’ [-fpermissive]

This can be solved by adding in cmake : set(CMAKE_CXX_FLAGS "-fpermissive -std=c++0x"). This point solves the issue but is there a better way to solve this problem?

Build fails on ubuntu-xenial (cmake 3.5.1, https://github.com/mkoeppe/PySCIPOpt/actions/runs/3457453303/jobs/5770894994)

Build succeeds on linuxmint-19 (cmake 3.10.2, https://github.com/mkoeppe/PySCIPOpt/actions/runs/3457453303/jobs/5770895677)

So it would make sense to use cmake_minimum_required(VERSION 3.10)

Minimal repo with SCIP, SoPLEX as submodules and a cmake

Hello Team,

I apologize if this is not the best place to post this request for help; having spent a few days trying to read documentation and figure out what to do. I need to get the entire search tree used during computation of a solution to an LP. This tree I assume would have unexplored nodes, pruned nodes etc. Is this possible on SCIP? Thanks for your help and guidance.

I compiled SCIP 7.0.3 on Mac and I am coding on C++.

Hi, I'm trying to use concurrentopt mode in SCIP. I compiled with CPLEX and IPOPT. While configuring with CMake I activated OpenMP library. So there is no problem with functionality. But my problem is working with Pyomo. Pyomo can not use internal functions as far as I know. I checked "scip --help" command and there is "-c "command" : execute single line of dialog commands (can be used multiple times)". So that I decided to pass "-c concurrentopt" but its not working.
I tried "scip -c concurrentopt -f example.nl" command and I get: "cannot mix batch mode '-c' and '-b' with file mode '-f'"
Is there any other alternatives to run parallel in default?