Re: [Numpy-discussion] Regarding Matrices

[Nils W. <nw...@ia...>]

On Mon, 14 Aug 2006 21:58:50 +0200
  Sven Schreiber <sve...@gm...> wrote:
> Hi,
>=20
> Satya Upadhya schrieb:
>=20
>>>>> from Numeric import *
>=20
> Well this list is about the numpy package, but anyway...
>=20
>> the power function is giving a resultant matrix in which=20
>>each element of
>> matrix B is raised to the power of 0 so as to make it 1.=20
>>But, taken as a
>> whole i.e. matrix B to the power of 0 should have given=20
>>the identity
>> matrix.
>=20
> afaik, in numpy terms if you are dealing with a numpy=20
>array, such
> functions are elementwise by design.
> In contrast, if you have a numpy matrix (a special=20
>subclass of the array
> class) --constructed e.g. as mat(eye(3))-- then power is=20
>redefined to be
> the matrix power; at least that's the rule for the **=20
>operator, not 100%
> sure if for the explicit power() function as well, but I=20
>suppose so.
>=20
>> =20
>> Also, what is the procedure for taking the log of an=20
>>entire matrix
>> (log(A) where A is a matrix takes the log of every=20
>>individual element in
>> A, but thats not the same as taking the log of the=20
>>entire matrix)
>=20
> I don't understand what you want, how do you take the=20
>log of a matrix
> mathematically?
>=20
> -Sven
>=20
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Help on function logm in module scipy.linalg.matfuncs:

logm(A, disp=3D1)
     Matrix logarithm, inverse of expm.

Nils