Error in Python matrix calculation

In this case, if the matrix is not a square matrix, the following error will appear:

　　　　

It is worth noting that when we use it in this way, the program will run normally

It seems that we have obtained the inverse of a non square matrix

Now let’s verify:

If you look at it carefully, it’s not a unit array. I think this method is not feasible, but with the idea of blog rigor, I decided to see the results of the square array

seeing here, I found that the inversion of square matrix also appeared abnormal. I can’t help but look carefully. The original term which should be 0 is very small. Friends who have studied numerical analysis should know that this is a non-zero problem caused by the rounding error of computer, so we can regard both as unit matrix

note: don’t convert the data type at will here, because converting the data type will result in the loss of data accuracy. For example, the unit matrix mentioned above will change when converting the data type, and a bit on the diagonal line may become 0. the unit matrix mentioned above will change when converting the data type