possible bug in example code

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	For demonstration purposes, let us consider the problem of linear regression.
	A matrix of predictors $\bm X \in \mathcal{R}^{n \times d}$
	and a vector of responses $\bm y \in \mathcal{R}^n$ is given.
	The task is to find the best linear model $\bm \Phi \in \mathcal{R}^d$,

	arma::mat X; arma::vec y;
	// ... set the contents of X and y here ...
	arma::mat phi_star(X.n_rows, 1, arma::fill::randu); // initial point (uniform random)
	LinearRegressionFn f(X, y);

	double Evaluate(const arma::mat& phi)
	{ const arma::vec tmp = X * phi - y; return arma::dot(tmp,tmp); }