wolffd@0: function g = rosegrad(x)
wolffd@0: %ROSEGRAD Calculate gradient of Rosenbrock's function.
wolffd@0: %
wolffd@0: %	Description
wolffd@0: %	G = ROSEGRAD(X) computes the gradient of Rosenbrock's function at
wolffd@0: %	each row of X, which should have two columns.
wolffd@0: %
wolffd@0: %	See also
wolffd@0: %	DEMOPT1, ROSEN
wolffd@0: %
wolffd@0: 
wolffd@0: %	Copyright (c) Ian T Nabney (1996-2001)
wolffd@0: 
wolffd@0: % Return gradient of Rosenbrock's test function
wolffd@0: 
wolffd@0: nrows = size(x, 1);
wolffd@0: g = zeros(nrows,2);
wolffd@0: 
wolffd@0: g(:,1) = -400 * (x(:,2) - x(:,1).^2) * x(:,1) - 2 * (1 - x(:,1));
wolffd@0: g(:,2) = 200 * (x(:,2) - x(:,1).^2);