Le 31/08/2011 18:09, Gilles Sadowski a écrit :
Hello.
Hi Gilles,
In the "AbstractLeastSquaresOptimizer" class (package "optimization"), there
is (at lines 238-247):
---CUT---
jF = f.jacobian();
this.residuals = new double[target.length];
// Arrays shared with the other private methods.
point = startPoint.clone();
rows = target.length;
cols = point.length;
weightedResidualJacobian = new double[rows][cols];
this.weightedResiduals = new double[rows];
---CUT---
Is it necessary to impose the layout of "jF"? Indeed, depending on the
implementation of the "jacobian()" method, one could have
---CUT---
rows = point.length;
cols = target.length;
---CUT---
instead. And it is not obvious from the documentation which it should be.
If which data goes into which of the matrix dimensions is not important, is
a way to specify which is which, so that both layout can be used (at the
user's discretion)?
If the layout cannot be decided by the user, it should probably stand out
somewhere in the documentation.
In fact, I have always seen Jacobians using this layout, so from my
point of view it was standard. I am conforted in this view by
<http://mathworld.wolfram.com/Jacobian.html>.
So I would prefer to see improved documentation rather than providing a
non-standard layout. I think you have already done this doc improvement
(I am trying to read all the mails that have arrived during my 2 days
unconnected ...)
best regards,
Luc
Best regards,
Gilles
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