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

---
 Utilib/src/ALDDLM.f | 75 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100644 Utilib/src/ALDDLM.f

(limited to 'Utilib/src/ALDDLM.f')

diff --git a/Utilib/src/ALDDLM.f b/Utilib/src/ALDDLM.f
new file mode 100644
index 0000000..f0bf4ba
--- /dev/null
+++ b/Utilib/src/ALDDLM.f
@@ -0,0 +1,75 @@
+*DECK ALDDLM
+      SUBROUTINE ALDDLM (L4,ASS,VEC,Z,MU1,ITY)
+*
+*-----------------------------------------------------------------------
+*
+*Purpose:
+* multiplication of a symmetric matrix in compressed diagonal storage
+* mode by a vector.
+* Double precision version.
+*
+*Copyright:
+* Copyright (C) 1989 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
+* L4      order of the coefficient matrix.
+* ASS     coefficient matrix in compressed diagonal storage mode.
+*         DIMENSION ASS(MU1(L4))
+* VEC     vector to multiply.
+* Z       vector that will be added to the result if ITY=2.
+* MU1     position of each diagonal element in vector ASS.
+* ITY     type of multiplication (ITY=1: Z=ASS*VEC;
+*         ITY=2: Z=Z+(ASS-DIAG(ASS))*VEC).
+*
+*Parameters: output
+* Z       solution of the multiplication.
+*
+*-----------------------------------------------------------------------
+*
+*----
+*  SUBROUTINE ARGUMENTS
+*----
+      INTEGER L4,MU1(L4),ITY
+      DOUBLE PRECISION ASS(*),VEC(L4),Z(L4)
+*----
+*  LOCAL VARIABLES
+*----
+      DOUBLE PRECISION ZK
+*
+      GO TO (10,60),ITY
+*
+* CALCULATION OF Z=ASS*VEC.
+   10 Z(1)=ASS(MU1(1))*VEC(1)
+      I1=MU1(1)+1
+      DO 50 K=2,L4
+      I2=MU1(K)
+      KEY1=I2-K
+      ZK=0.0D0
+      DO 30 L=I1-I2+K,K-1
+      ZK=ZK+ASS(KEY1+L)*VEC(L)
+      Z(L)=Z(L)+ASS(KEY1+L)*VEC(K)
+   30 CONTINUE
+      Z(K)=ZK+ASS(KEY1+K)*VEC(K)
+      I1=I2+1
+   50 CONTINUE
+      RETURN
+*
+* CALCULATION OF Z=Z+(ASS-DIAG(ASS))*VEC.
+   60 I1=MU1(1)+1
+      DO 80 K=2,L4
+      I2=MU1(K)
+      KEY1=I2-K
+      DO 70 L=I1-I2+K,K-1
+      Z(K)=Z(K)+ASS(KEY1+L)*VEC(L)
+      Z(L)=Z(L)+ASS(KEY1+L)*VEC(K)
+   70 CONTINUE
+      I1=I2+1
+   80 CONTINUE
+      RETURN
+      END
-- 
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