Singular matrix issue with Numpy

matrix, numpy, python

Solution

The matrix you pasted

[[   1,    8,   50],
 [   8,   64,  400],
 [  50,  400, 2500]]

Has a determinant of zero. This is the definition of a Singular matrix (one for which an inverse does not exist)

http://en.wikipedia.org/wiki/Invertible_matrix

Problem

I am trying to multiply a vector(3 by 1) by its transpose(1 by 3). I get a (3 by 3) array but I cannot get its inverse. Any idea why? ``` import numpy as np c=array([1, 8, 50]) np.transpose(c[np.newaxis]) * c array([[ 1, 8, 50], [ 8, 64, 400], [ 50, 400, 2500]]) np.linalg.inv(np.transpose(c[np.newaxis]) * c) Traceback (most recent call last): File "<console>", line 1, in <module> File "C:\Python26\lib\site-packages\numpy\linalg\linalg.py", line 445, in inv return wrap(solve(a, identity(a.shape[0], dtype=a.dtype))) File "C:\Python26\lib\site-packages\numpy\linalg\linalg.py", line 328, in solve raise LinAlgError, 'Singular matrix' LinAlgError: Singular matrix ```

Original source