[SciPy-User] fmin_bfgs stuck in infinite loop

josef.pktd@gmai... josef.pktd@gmai...
Mon Oct 24 12:56:25 CDT 2011


On Mon, Oct 24, 2011 at 1:50 PM, Johann Cohen-Tanugi
<johann.cohentanugi@gmail.com> wrote:
> Hello,
> the OP is a colleague of mine and I looked quickly at the code. The infinite
> loop in the OP's illustrating script comes from the "while 1" loop in l.144
> of linesearch.py : becuse phi0 is np.nan, phi1 is returned as np.nan as
> well, and the break condition is never met. There is an easy fix :
>     while 1:
>         stp, phi1, derphi1, task = minpack2.dcsrch(alpha1, phi1, derphi1,
>                                                    c1, c2, xtol, task,
>                                                    amin, amax, isave, dsave)
>         if task[:2] == asbytes('FG') and not np.isnan(phi1):
>             alpha1 = stp
>             phi1 = phi(stp)
>             derphi1 = derphi(stp)
>         else:
>             break
>
> but it is not a nice kludge.... Is there a better way to secure this while 1
> loop? I am sure I am not covering all possible pathological cases with
> adding "not np.isnan(phi1)" in the code above.

Is this still a problem with 0.10 ?
I thought this fixed it, https://github.com/scipy/scipy/commit/a31acbf

Josef


>
> thoughts?
> Johann
>
> On 08/14/2011 01:38 AM, b9o2jnbm tsd71eam wrote:
>
> I have run into a frustrating problem where scipy.optimize.fmin_bfgs will
> get stuck in an infinite loop.
>
> I have submitted a bug report:
>
> http://projects.scipy.org/scipy/ticket/1494
>
> but would also like to see if anybody on this list has any suggestions or
> feedback.
>
> Thanks,
>
> --
> This message has been scanned for viruses and
> dangerous content by MailScanner, and is
> believed to be clean.
>
> _______________________________________________
> SciPy-User mailing list
> SciPy-User@scipy.org
> http://mail.scipy.org/mailman/listinfo/scipy-user
>
> _______________________________________________
> SciPy-User mailing list
> SciPy-User@scipy.org
> http://mail.scipy.org/mailman/listinfo/scipy-user
>
>


More information about the SciPy-User mailing list