A-M baby

Task/Identity-matrix/Fortran/identity-matrix.f

@@ -0,0 +1,23 @@
+program identitymatrix
+
+  real, dimension(:, :), allocatable :: I
+  character(len=8) :: fmt
+  integer :: ms, j
+
+  ms = 10   ! the desired size
+
+  allocate(I(ms,ms))
+  I = 0                           ! Initialize the array.
+  forall(j = 1:ms) I(j,j) = 1     ! Set the diagonal.
+
+  ! I is the identity matrix, let's show it:
+
+  write (fmt, '(A,I2,A)') '(', ms, 'F6.2)'
+  ! if you consider to have used the (row, col) convention,
+  ! the following will print the transposed matrix (col, row)
+  ! but I' = I, so it's not important here
+  write (*, fmt) I(:,:)
+
+  deallocate(I)
+
+end program identitymatrix