From 7dfcc480ba1e19bd3232349fc733caef94034292 Mon Sep 17 00:00:00 2001
From: stainer_t <thomas.stainer@oecd-nea.org>
Date: Mon, 8 Sep 2025 13:48:49 +0200
Subject: Initial commit from Polytechnique Montreal

---
 Trivac/src/TRIASH.f | 75 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100755 Trivac/src/TRIASH.f

(limited to 'Trivac/src/TRIASH.f')

diff --git a/Trivac/src/TRIASH.f b/Trivac/src/TRIASH.f
new file mode 100755
index 0000000..0433dc2
--- /dev/null
+++ b/Trivac/src/TRIASH.f
@@ -0,0 +1,75 @@
+*DECK TRIASH
+      SUBROUTINE TRIASH(IELEM,NBMIX,LL4F,NBLOS,MAT,SIDE,ZZ,FRZ,SGD,KN,
+     > IPERT,VEC)
+*
+*-----------------------------------------------------------------------
+*
+*Purpose:
+* Assembly of a diagonal system matrix corresponding to a single cross
+* section type (Thomas-Raviart-Schneider dual cases). Note: vector VEC
+* should be initialized by the calling program.
+*
+*Copyright:
+* Copyright (C) 2006 Ecole Polytechnique de Montreal
+* This library is free software; you can redistribute it and/or
+* modify it under the terms of the GNU Lesser General Public
+* License as published by the Free Software Foundation; either
+* version 2.1 of the License, or (at your option) any later version
+*
+*Author(s): A. Hebert
+*
+*Parameters: input
+* IELEM   degree of the Lagrangian finite elements.
+* NBMIX   maximum number of material mixtures.
+* LL4F    total number of flux unknowns per group.
+* NBLOS   number of lozenges per direction, taking into account
+*         mesh-splitting.
+* MAT     mixture index assigned to each element.
+* SIDE    side of an hexagon.
+* ZZ      Z-directed mesh spacings.
+* FRZ     volume fractions for the axial SYME boundary condition.
+* SGD     cross section per material mixture.
+* KN      ADI permutation indices for the volumes.
+* IPERT   mixture permutation index.
+*
+*Parameters: output
+* VEC     diagonal system matrix.
+*
+*-----------------------------------------------------------------------
+*
+*----
+*  SUBROUTINE ARGUMENTS
+*----
+      PARAMETER(MAXIEL=3)
+      INTEGER IELEM,NBMIX,LL4F,NBLOS,MAT(3,NBLOS),KN(NBLOS,3),
+     1 IPERT(NBLOS)
+      REAL SIDE,ZZ(3,NBLOS),FRZ(NBLOS),SGD(NBMIX),VEC(LL4F)
+*----
+*  LOCAL VARIABLES
+*----
+      DOUBLE PRECISION TTTT,VOL0,SIG
+*
+      TTTT=0.5D0*SQRT(3.D00)*SIDE*SIDE
+      NUM=0
+      DO 20 KEL=1,NBLOS
+      IF(IPERT(KEL).EQ.0) GO TO 20
+      IBM=MAT(1,IPERT(KEL))
+      IF(IBM.EQ.0) GO TO 20
+      NUM=NUM+1
+      VOL0=TTTT*ZZ(1,IPERT(KEL))*FRZ(KEL)
+      SIG=SGD(IBM)
+      DO 12 K3=0,IELEM-1
+      DO 11 K2=0,IELEM-1
+      DO 10 K1=0,IELEM-1
+      JND1=(NUM-1)*IELEM**3+K3*IELEM**2+K2*IELEM+K1+1
+      JND2=(KN(NUM,1)-1)*IELEM**3+K3*IELEM**2+K2*IELEM+K1+1
+      JND3=(KN(NUM,2)-1)*IELEM**3+K3*IELEM**2+K2*IELEM+K1+1
+      VEC(JND1)=VEC(JND1)+REAL(VOL0*SIG)
+      VEC(JND2)=VEC(JND2)+REAL(VOL0*SIG)
+      VEC(JND3)=VEC(JND3)+REAL(VOL0*SIG)
+   10 CONTINUE
+   11 CONTINUE
+   12 CONTINUE
+   20 CONTINUE
+      RETURN
+      END
-- 
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