VectorMath.f90

MODULE VectorMath

  IMPLICIT NONE

CONTAINS

!**** FUNCTIONS RETURNING SCALARS

  PURE REAL(8) FUNCTION DotProduct(p,q,n) result(pdotq); IMPLICIT NONE

    integer, intent(in) :: n
    real(8), intent(in) :: p(n), q(n)
    integer :: i

    pdotq = 0.0d0

    do i = 1, n
      pdotq = pdotq + (p(i) * q(i))
    enddo

  END FUNCTION DotProduct

!*

  PURE REAL(8) FUNCTION EuclideanNorm(vector,n) result(r); IMPLICIT NONE

    integer, intent(in) :: n
    real(8), intent(in) :: vector(n)

    r = dsqrt(DotProduct(vector,vector,n))

  END FUNCTION EuclideanNorm

!**** FUNCTIONS RETURNING VECTORS

  PURE FUNCTION NormaliseVector(p,n); IMPLICIT NONE

    integer, intent(in) :: n
    real(8), intent(in) :: p(n)
    real(8) :: NormaliseVector(n)

    NormaliseVector = p(:) / EuclideanNorm(p,n)

  END FUNCTION NormaliseVector

!*

  PURE FUNCTION CrossProduct(p,q); IMPLICIT NONE

    real(8), intent(in)  :: p(3), q(3)
    real(8) :: CrossProduct(3)

    CrossProduct(1) = p(2)*q(3) - p(3)*q(2)
    CrossProduct(2) = p(3)*q(1) - p(1)*q(3)
    CrossProduct(3) = p(1)*q(2) - p(2)*q(1)

  END FUNCTION CrossProduct

!*

END MODULE VectorMath