https://cyana.org/w/index.php?action=history&feed=atom&title=CYANA_Commands%3A_gradientCYANA Commands: gradient - Revision history2026-04-20T02:22:35ZRevision history for this page on the wikiMediaWiki 1.45.1https://cyana.org/w/index.php?title=CYANA_Commands:_gradient&diff=4550&oldid=prevAdmin: 1 revision2009-01-28T23:35:41Z<p>1 revision</p>
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== Parameters ==<br />
<br />
; step=''real'': (default: 0.000001)<br />
; cutoff=''real'': (default: -1.0)<br />
<br />
== Description ==<br />
<br />
This function computes the gradient, i.e. the partial derivatives<br />
of the target function against the torsion angle, numerically and<br />
compares the result with the gradient computed by the (normal)<br />
analytic method. The numerical derivatives are calculated with the<br />
step size given by the '''step''' parameter, as well as by using a 10<br />
times smaller and a 10 times larger step size. The deviation of the<br />
analytical gradient from the three numerically calculated gradient<br />
values are reported for all torsion angles for which the maximal<br />
absolute deviation exceeds the value set by the '''cutoff''' parameter.<br />
<br />
This command is useful to check the analytical gradient calculation<br />
for correctness after a change of the target function and gradient<br />
calculation.</div>Admin