Cholesky decomposition : cholesky

### 2.48.1 Cholesky decomposition : `cholesky`

`cholesky` takes as argument a square symetric positive definite matrix `M` of size n.
`cholesky` returns a symbolic or numeric matrix `P`. `P` is a lower triangular matrix such that :

`tran(P)*P=M`

Input :

`cholesky([[1,1],[1,5]])`

Output :

`[[1,0],[1,2]]`

Input :

`cholesky([[3,1],[1,4]])`

Output :

`[[sqrt(3),0],[(sqrt(3))/3,(sqrt(33))/3]]`

Input :

`cholesky([[1,1],[1,4]])`

Output :

`[[1,0],[1,sqrt(3)]]`

Warning If the matrix argument A is not a symetric matrix, `cholesky` does not return an error, instead `cholesky` will use the symetric matrix B of the the quadratic form q corresponding to the (non symetric) bilinear form of matrix A.
Input :

`cholesky([[1,-1],[-1,4]])`

or :

`cholesky([[1,-3],[1,4]])`

Output :

`[[1,0],[-1,sqrt(3)]]`