> One more time, could you do the following sequence of commands so that I
> can report them to the numpy mailing list. I've left the output from my
> run; it's interesting that the numpy.linalg.inv on my computer gives the
> same ridiculous answers that your scipy.linalg.inv command gives. It
> looks like it is scaling by dividing by the determinant or something.
>
> sage: import numpy
> sage: a=numpy.array([[1,2,3],[4,5,6],[7,8,9]],dtype="float64")
> sage: import scipy
> sage: import scipy.linalg
> sage: import numpy.linalg
> sage: scipy.linalg.det(a)
> 0.0
> sage: scipy.linalg.inv(a)
> ---------------------------------------------------------------------------
> LinAlgError Traceback (most recent call
> [snip]
> LinAlgError: singular matrix
> sage: numpy.linalg.det(a)
> -1.3325928902019335e-15
> sage: numpy.linalg.inv(a)
>
> array([[ 2.25125019e+15, -4.50250038e+15, 2.25125019e+15],
> [ -4.50250038e+15, 9.00500077e+15, -4.50250038e+15],
> [ 2.25125019e+15, -4.50250038e+15, 2.25125019e+15]])
I get this:
sage: scipy.linalg.det(a)
0.0
sage: scipy.linalg.inv(a)
array([[ -4.50359963e+15, 9.00719925e+15, -4.50359963e+15],
[ 9.00719925e+15, -1.80143985e+16, 9.00719925e+15],
[ -4.50359963e+15, 9.00719925e+15, -4.50359963e+15]])
sage: numpy.linalg.det(a)
6.6613381477509392e-16
sage: numpy.linalg.inv(a)
array([[ -4.50359963e+15, 9.00719925e+15, -4.50359963e+15],
[ 9.00719925e+15, -1.80143985e+16, 9.00719925e+15],
[ -4.50359963e+15, 9.00719925e+15, -4.50359963e+15]])
John
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