[SciPy-user] null space of a matrix
ryanfedora at comcast.net
Wed Jun 29 14:59:57 CDT 2005
This is a completely trivial addition to Richard's submission, but here
is the function I am using to implement the null function if anyone
wants to copy and paste it into there own code:
def null(A, eps=1e-15):
u, s, vh = scipy.linalg.svd(A)
null_mask = (s <= eps)
null_space = scipy.compress(null_mask, vh, axis=0)
(this assumes you have already got an import scipy somewhere in the file)
(It made more sense to me to return column vectors.)
Ryan Krauss wrote:
> Thanks Robert. This works very well. You seem to always submit high
> quality input to the list.
> Robert Kern wrote:
>> Ryan Krauss wrote:
>>> This is probably a Numeric question, but is there an easy way to
>>> find the null space of a matrix in SciPy?
>> The SVD is one way.
>> u, s, vh = linalg.svd(A)
>> null_mask = (s <= eps)
>> null_space = compress(null_mask, vh, axis=0)
>> The rows in null_space span the null space of A.
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