From 8018440410fac858f9a5ed2fb9f2c4ec4963c4b3 Mon Sep 17 00:00:00 2001
From: AbdAmmar <abd.ammar.phys@gmail.com>
Date: Thu, 25 Jan 2024 22:13:13 +0100
Subject: [PATCH] OPENMP & DGEMM in pseudo_inv

---
 src/utils/linear_algebra.irp.f | 57 +++++++++++++++++++++++-----------
 1 file changed, 39 insertions(+), 18 deletions(-)

diff --git a/src/utils/linear_algebra.irp.f b/src/utils/linear_algebra.irp.f
index 314ad4f6..a67a219c 100644
--- a/src/utils/linear_algebra.irp.f
+++ b/src/utils/linear_algebra.irp.f
@@ -1321,19 +1321,22 @@ subroutine get_inverse(A,LDA,m,C,LDC)
   deallocate(ipiv,work)
 end
 
-subroutine get_pseudo_inverse(A,LDA,m,n,C,LDC,cutoff)
-  implicit none
+subroutine get_pseudo_inverse(A, LDA, m, n, C, LDC, cutoff)
+
   BEGIN_DOC
   ! Find C = A^-1
   END_DOC
-  integer, intent(in)            :: m,n, LDA, LDC
-  double precision, intent(in)   :: A(LDA,n)
-  double precision, intent(in)   :: cutoff
-  double precision, intent(out)  :: C(LDC,m)
 
-  double precision, allocatable  :: U(:,:), D(:), Vt(:,:), work(:), A_tmp(:,:)
-  integer                        :: info, lwork
-  integer                        :: i,j,k
+  implicit none
+  integer, intent(in)           :: m, n, LDA, LDC
+  double precision, intent(in)  :: A(LDA,n)
+  double precision, intent(in)  :: cutoff
+  double precision, intent(out) :: C(LDC,m)
+
+  integer                       :: info, lwork
+  integer                       :: i, j, k, n_svd
+  double precision, allocatable :: U(:,:), D(:), Vt(:,:), work(:), A_tmp(:,:)
+
   allocate (D(n),U(m,n),Vt(n,n),work(1),A_tmp(m,n))
   do j=1,n
     do i=1,m
@@ -1355,22 +1358,40 @@ subroutine get_pseudo_inverse(A,LDA,m,n,C,LDC,cutoff)
     stop 1
   endif
 
-  do i=1,n
-    if (D(i)/D(1) > cutoff) then
-      D(i) = 1.d0/D(i)
+  n_svd = 0
+  do i = 1, n
+    if(D(i)/D(1) > cutoff) then
+      D(i) = 1.d0 / D(i)
+      n_svd = n_svd + 1
     else
       D(i) = 0.d0
     endif
   enddo
+  print*, ' n_svd = ', n_svd
 
-  C = 0.d0
-  do i=1,m
-    do j=1,n
-      do k=1,n
-        C(j,i) = C(j,i) + U(i,k) * D(k) * Vt(k,j)
-      enddo
+  !$OMP PARALLEL       &
+  !$OMP DEFAULT (NONE) &
+  !$OMP PRIVATE (i, j) &
+  !$OMP SHARED (n, n_svd, D, Vt)
+  !$OMP DO
+  do j = 1, n
+    do i = 1, n_svd
+      Vt(i,j) = D(i) * Vt(i,j)
     enddo
   enddo
+  !$OMP END DO
+  !$OMP END PARALLEL
+
+  call dgemm("N", "N", m, n, n_svd, 1.d0, U, m, Vt, n, 0.d0, C, LDC)
+
+  !C = 0.d0
+  !do i=1,m
+  !  do j=1,n
+  !    do k=1,n
+  !      C(j,i) = C(j,i) + U(i,k) * D(k) * Vt(k,j)
+  !    enddo
+  !  enddo
+  !enddo
 
   deallocate(U,D,Vt,work,A_tmp)