[SciPy-user] Type handling of matrices
pearu at scipy.org
Thu Nov 11 02:44:40 CST 2004
On Thu, 11 Nov 2004, Nils Wagner wrote:
> Gary Ruben wrote:
>> Hi Nils,
>> How about transposing and subtracting it?
> That's the definition of a real symmetric matrix
> A = transpose(A)
> In case of complex matrices we have
> A = conj(transpose(A))
> I am looking for a built-in function
> which returns
> 1 if A is hermitian
> 0 if A is non-hermitian
> How about similar functions for
> A.issingular (singular from a numerical point of view)
> A.isspd (symmetric positive definite) This might be useful with respect to
> iterative solvers. AFAIK linalg.cg is restricted to spd matrices.
Methods (not attributes) A.is<property> can be defined for sparse
matrices, in fact, sparse.spmatrix should take advantage of using
For full matrices, is<property> must probably be a function as we cannot
change Numeric of numarray in this way (unless we subclass Matrix). They
can be implemented in scipy_base/matrix_base.py, for instance.
<property> = symmetric | hermitian | singular | positive | negative
| nonnegative | nonpositive
All these predicate functions must have optional tolerance
argument to take into account numerical errors that accumulate
when computing eigenvalues..
More information about the SciPy-user