fsolve features

[John W. Eaton]

On  5-Jul-1999, Rolf Fabian <address@hidden> wrote a number of
complaints about Octave's fsolve function including

  * fsolve is not able to compute complex-valued solutions.

  * fsolve discards the imaginary part of complex-valued initial guesses.

  * fsolve discards the imaginary part of complex-valued function
    evaluations.

Note that warnings about discarding the imaginary part of a complex
value are given by default, but may be suppressed depending on the
setting of the built-in variable ok_to_lose_imaginary_part.

The problem is that fsolve is not intended to handle complex-valued
functions or find complex-valued solutions.  It is based on Minpack's
hybrd function, which is only good finding real-valued solutions for
real-valued functions.

If you have a better solution, please consider providing it as an
alternative (submit it to octave-sources, for starters).  If it is
really better, then perhaps it can become the default method for
fsolve.

Thanks,

jwe



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