Foortran Toolkit

Fortran toolkit

Borja Petit

diag

function diag(mat) result(vec)
  implicit none
  real(kind=8) :: mat(:,:)              ! input
  real(kind=8) :: vec(size(mat,dim=1))  ! output: vector with main diagonal of mat

This function returns the main diagonal of a matric mat.

Dependencies: error

(back to index)

Example

mat(:,1) = (/ 1.0, 2.0, 1.0 /)
mat(:,2) = (/ 3.0, 3.0, 4.0 /)
mat(:,3) = (/ 5.0, 1.0, 3.0 /)

vec = diag(mat)

print * , 'vec = ', vec   ! vec =  1.00  3.00  3.00