From 560e148807b688d20275985646225423a8ee8733 Mon Sep 17 00:00:00 2001
From: Wojtek Kosior <kwojtus@protonmail.com>
Date: Sun, 30 Jun 2019 22:09:14 +0200
Subject: sum values in a smarter order

---
 src/quadratures.f90 | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

(limited to 'src/quadratures.f90')

diff --git a/src/quadratures.f90 b/src/quadratures.f90
index c2be860..35b28c4 100644
--- a/src/quadratures.f90
+++ b/src/quadratures.f90
@@ -46,10 +46,11 @@ CONTAINS
     procedure(funint) :: fun
     procedure(quadrature) :: quad
     
-    real(kind=8) :: val, subinterval_width, qbeg, qend
+    real(kind=8) :: val, subinterval_width, qbeg, qend, partsums(48)
+    logical :: partsums_mask(48) = .true.
     real(kind=8), allocatable :: partval[:]
     
-    integer(kind=8) :: min_i, max_i, i, subintervals_per_thread
+    integer(kind=8) :: min_i, max_i, i, j, subintervals_per_thread
     integer(kind=4) :: im
 
     allocate(partval[*])
@@ -68,9 +69,25 @@ CONTAINS
     DO i = min_i, max_i
        qend = ibeg + i * subinterval_width
        qbeg = ibeg + (i - 1) * subinterval_width
-       partval = partval + quad(qbeg, qend, fun)
+       val = quad(qbeg, qend, fun)
+
+       DO j = 1, 48
+          IF (partsums_mask(j)) THEN
+             partsums_mask(j) = .false.
+             partsums(j) = val
+             EXIT
+          END IF
+
+          val = val + partsums(j)
+          partsums_mask(j) = .true.
+       END DO
     END DO
 
+    partval = 0
+    DO j = 1, 48
+       IF (.not. partsums_mask(j)) partval = partval + partsums(j)
+    END DO
+    
     IF (this_image() == 1 .and. num_images() > 1) THEN
        sync images([(im, im = 2, num_images())])
        partval = partval + sum([(partval[im], im = 2, num_images())])
-- 
cgit v1.2.3