[SciPy-user] do complex numbers default to double precision?

Nils Wagner nwagner at mecha.uni-stuttgart.de
Thu Jun 30 06:03:53 CDT 2005


Ryan Krauss wrote:

> I have a matrix that is a function of a complex valued input.  I am 
> trying to find that value of that input that drives the determinant of 
> the matrix to zero.  I am searching for this value using fmin. The 
> error I am trying to minimize is the abs(det(complex matrix)).

It's not a good idea to use the determinant directly since det(A) is a 
rapidly varying function. As far as I understand your problem,
you are interested in the solution of a two-parameter nonlinear 
eigenvalue problem. Is that correct ? How about the size of your complex 
matrix A ?

Nils

> I don't seem to be able to drive this error lower that roughly 9e-17, 
> regardless of the values for ftol and xtol I use.
>
> Am I hitting some internal limitation?  Are complex values by default 
> single or double precision?
>
> Thanks,
>
> Ryan
>
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