CYANA Command: gradient

Parameters

step=real

(default: 0.000001)

cutoff=real

(default: -1.0)

Description

Computes the gradient, i.e. the partial derivatives of the target function against the torsion angle, numerically and compares the result with the gradient computed by the (normal) analytic method. The numerical derivatives are calculated with the given step size given, as well as with a 10 times smaller and a 10 times larger step size. The deviation of the analytical gradient from the three numerically calculated gradient values are reported for all torsion angles for which the maximal absolute deviation exceeds the given cutoff value. This command is useful to check the analytical gradient calculation for correctness after a change to the implementation of the target function and/or gradient calculation.