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/FLDTN2.f | 85 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 85 insertions(+)
 create mode 100755 Trivac/src/FLDTN2.f

(limited to 'Trivac/src/FLDTN2.f')

diff --git a/Trivac/src/FLDTN2.f b/Trivac/src/FLDTN2.f
new file mode 100755
index 0000000..50a80f4
--- /dev/null
+++ b/Trivac/src/FLDTN2.f
@@ -0,0 +1,85 @@
+*DECK FLDTN2
+      SUBROUTINE FLDTN2 (NEL,LL4,IELEM,CYLIND,EVECT,XX,DD,MAT,VOL,IDL,
+     1 KN,LC,T,TS)
+*
+*-----------------------------------------------------------------------
+*
+*Purpose:
+* Compute the integrated flux in each finite element for a Lagrangian
+* finite element discretization in Cartesian or cylindrical geometry.
+*
+*Copyright:
+* Copyright (C) 2002 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
+* NEL     number of finite elements.
+* LL4     order of system matrices.
+* IELEM   degree of the finite elements.
+* CYLIND  cylindrical geometry flag (set with CYLIND=.true.).
+* EVECT   unknown vector containing the variational coefficients in
+*         locations 1 to LL4.
+* XX      X-directed mesh spacings.
+* DD      used with cylindrical geometry.
+* MAT     mixture index assigned to each element.
+* VOL     volume of each element.
+* IDL     indices pointing to integrated fluxes in EVECT array.
+* KN      element-ordered unknown list.
+* LC      order of the finite element basis.
+* T       linear product vector.
+* TS      linear product vector.
+*
+*Parameters: output
+* EVECT   unknown vector containing the integrated fluxes in location
+*         IDL(I).
+*
+*-----------------------------------------------------------------------
+*
+*----
+*  SUBROUTINE ARGUMENTS
+*----
+      INTEGER NEL,LL4,IELEM,MAT(NEL),IDL(NEL),KN(NEL*(IELEM+1)**3),LC
+      REAL EVECT(LL4+NEL),XX(NEL),DD(NEL),VOL(NEL),T(LC),TS(LC)
+      LOGICAL CYLIND
+*----
+*  LOCAL VARIABLES
+*----
+      INTEGER IJ1(125),IJ2(125),IJ3(125)
+*
+      LL=LC*LC*LC
+      DO 100 L=1,LL
+      L1=1+MOD(L-1,LC)
+      L2=1+(L-L1)/LC
+      L3=1+MOD(L2-1,LC)
+      IJ1(L)=L1
+      IJ2(L)=L3
+      IJ3(L)=1+(L2-L3)/LC
+  100 CONTINUE
+*
+      NUM1=0
+      DO 130 K=1,NEL
+      IF(MAT(K).EQ.0) GO TO 130
+      EVECT(IDL(K))=0.0
+      IF(VOL(K).EQ.0.0) GO TO 120
+      DO 110 I=1,LL
+      IND1=KN(NUM1+I)
+      IF(IND1.EQ.0) GO TO 110
+      I1=IJ1(I)
+      I2=IJ2(I)
+      I3=IJ3(I)
+      IF(CYLIND) THEN
+         SS=(T(I1)+TS(I1)*XX(K)/DD(K))*T(I2)*T(I3)
+      ELSE
+         SS=T(I1)*T(I2)*T(I3)
+      ENDIF
+      EVECT(IDL(K))=EVECT(IDL(K))+SS*EVECT(IND1)
+  110 CONTINUE
+  120 NUM1=NUM1+LL
+  130 CONTINUE
+      RETURN
+      END
-- 
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