[SciPy-user] do complex numbers default to double precision?
ryanfedora at comcast.net
Thu Jun 30 07:56:26 CDT 2005
The matrix is currently 4x4 but will grow to probably 6x6. It is
definitely nonlinear. The matrix contains sinh, cosh, sin, and cos. I
am using the transfer matrix method to analyze structures. When you say
two-parameter, do you mean the real and imaginary part of the
independent variable? I guess you are right that I don't necessarily
need to use the determinant. In order to satisfy the boundary
conditions of the problem this 4x4 or 6x6 matrix (which is really a
submatrix of an 8x8 or 12x12) must have a null space. So, what would be
the better thing to look for? An eignevalue that approaches 0?
Nils Wagner wrote:
> 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 ?
>> 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?
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