matinv_3x3 Function

pure function matinv_3x3(a) result(b)

   !> Matrix
   real(wp), intent(in) :: a(3, 3)

   !> Inverse matrix
   real(wp) :: b(3, 3)

   real(wp) :: detinv

   ! Calculate the inverse determinant of the matrix
   detinv = 1.0_wp/matdet_3x3(a)

   ! Calculate the inverse of the matrix
   b(1, 1) = +detinv * (a(2, 2) * a(3, 3) - a(2, 3) * a(3, 2))
   b(2, 1) = -detinv * (a(2, 1) * a(3, 3) - a(2, 3) * a(3, 1))
   b(3, 1) = +detinv * (a(2, 1) * a(3, 2) - a(2, 2) * a(3, 1))
   b(1, 2) = -detinv * (a(1, 2) * a(3, 3) - a(1, 3) * a(3, 2))
   b(2, 2) = +detinv * (a(1, 1) * a(3, 3) - a(1, 3) * a(3, 1))
   b(3, 2) = -detinv * (a(1, 1) * a(3, 2) - a(1, 2) * a(3, 1))
   b(1, 3) = +detinv * (a(1, 2) * a(2, 3) - a(1, 3) * a(2, 2))
   b(2, 3) = -detinv * (a(1, 1) * a(2, 3) - a(1, 3) * a(2, 1))
   b(3, 3) = +detinv * (a(1, 1) * a(2, 2) - a(1, 2) * a(2, 1))

end function matinv_3x3