stellinstall/svdinv2_8f_source.html

      SUBROUTINE svdinv2 (amat, u, vt, w, m)

!

!     Computes PSEUDO-INVERSE of AMAT, Given SVD matrices u,v and

!     weight array w

!

!     MIMICS svdinv, but uses u, vt, w computed from Lapack

!     IT IS ASSUMED THAT THE ORDERED WEIGHT ARRAY w HAS BEEN SET

!     (EXTERNALLY) TO ZERO WHERE THE WEIGHTS ARE TO BE NEGLECTED

!

!

      USE stel_kinds

      IMPLICIT NONE

!-----------------------------------------------

!   D u m m y   A r g u m e n t s

!C-----------------------------------------------

      INTEGER, INTENT(in)     :: m

      REAL(rprec), DIMENSION(m,m), INTENT(out)   :: amat

      REAL(rprec), DIMENSION(m,m), INTENT(inout) :: u, vt

      REAL(rprec), DIMENSION(m)                  :: w

!-----------------------------------------------

!   L o c a l   P a r a m e t e r s

!-----------------------------------------------

      REAL(rprec) :: zero = 0

!-----------------------------------------------

!   L o c a l   V a r i a b l e s

!-----------------------------------------------

      INTEGER :: i, j

!-----------------------------------------------

!

!     APEUDO-INV = V * WINV * UT

!     RECALL, VT = TRANSPOSE(V)

!


      DO i = 1, m

         IF (w(i) .gt. zero) THEN

!divide ith row of Utr by w(i)

            u(:m,i) = u(:m,i)/w(i)

         ELSE

!zero the infinite 1/weights

            u(:m,i) = zero   !1.E-10_dp*u(:m,i)

         END IF

      END DO


      amat = matmul(transpose(vt), transpose(u))


      END SUBROUTINE svdinv2