numpy - Inverse of a Matrix in Python -

Using numpy.linalg.inv (matrix) trying to reverse the matrix in the dragon , I get the singular matrix error Why does this happen? Does the matrix have anything to do with small things of values, the numbers in my matrix are probability and add up to 1.

It must be done very well in small things of values ​​in the matrix.

Some metrics that are not really, in fact, are mathematical singular (with zero determiners) completely singular from a practical perspective, in which the mathematical library is one that can not be processed properly Could.

Numerical analysis is difficult, as you know, and how well it deals with such situations, the matrix is ​​a measure of the quality of the library.