Based on grads cbar_line2.gs but with extra option -w for the
    linewidths. In this improved version, lines are only drawn if
    linestyle is not equal to zero. It turns off the string size
    definition, so the user can modify this outside.

    Based on cbar_line2w.gs but This version will draw the legend
    on a line.

    Modified version of grads cbarn that turn vpage off thus
    allowing a single bar under multiple panels. Written by diane
    stokes following discussions I started on grads mailing
    list. This is not available in grads webpage.

    Modified version of diane's cbarnv. Now she included a skip
    option, so the user can choose how many labels will be shown
    under the bar.

    Modified version of diane's cbarnv. I changed it to show the
    values in the middle of the each bar. The first and last
    colors are shown without the triangle. 

    Create a rainbow color sequence interpolating between two RGB
    colors. User can choose number of colors and color id.

    Draws a palette on the screen to allow the user to create a
    rainbow sequence by looking how colors looks like.

MATLAB script to open an image file and read the RGB
values. The user defines a regular grid at which the colors
will be read. Useful for copying the RGB values of some nice
colorbar in an image so that you can use the same colors in
grads (try with getcolors.png).

    Clear screen, display var with limits and add cbarn.
    Usage: dc var [cint [cmin [cmax]]]

    Clear screen, display var at specific leves and add cbarn.
    Usage: dd var clevs

    Draws a big arrow on the screen using world coordinates.

    Draws a line on the screen using world coordinates.

    Draws a marker on the screen using world coordinates.

    Draw a polygon on the screen using world coordinates.

    Draw a rectangle on the screen using world coordinates.

    Draw a polygon by hand, i.e., by clicking on the screen.

Bin Guan's histogram function

    Draws a box in the figure with a text inside with shortcuts
    for positioning at the corners.

Create a new variable as the average of the same variable
existing in multiple opened files.

Create a new variable as the standard deviation of the same
variable existing in multiple opened files.

Interpolates a field to an exact latitute or longitute

Draws a wind-rose from wind speed and direction

Let the user click in a map, an return the world coordinates. 

Return current time as 'YY MM dd hh mm', suitable to write to an
ascii file, for example.

    These will reinit grads and open all ctl files in a give
    directory using either 'open', 'sdfopen' or 'xdfopen'.

    Selects all different values of a field in a given area. The
    returning value of the function is the number of values and a
    global variable _mapval stores is defined to keep the values.

    Function grepfile can be used to grep only those lines from a
    file that match a given pattern. The result is the number of
    matching lines. The actual lines are stored in a global vector
    named _grepfile

    Function greptext can be used to grep only those lines from a
    text that match a given pattern. The result is the number of
    matching lines. The actual lines are stored in a global vector
    named _greptext

    Check each character in a string, returning true (1) or false
    (0) if the string as a whole can be considered a number.