Report bug on document of gmres

The example code for gmres with preconditioner has bug: the relative residual to plot from resvec should be resvec/norm(preconditioner\b), not resvec/norm(b).

A simple check is the relative residual should be 1 when interation = 0, since norm(Ax-b)/norm(b) = norm(b)/norm(b) = 1.

Answer 1

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