From bebf8c1313e60d5ac70c8b4f9a58a67f520e7d66 Mon Sep 17 00:00:00 2001
From: Arne Morten Kvarving <arne.morten.kvarving@sintef.no>
Date: Tue, 4 Oct 2022 12:27:50 +0200
Subject: [PATCH] added: SAM::getUniqueEqns

this returns the unique equations for a given element.
in particular it resolves MPC couplings
---
 src/LinAlg/SAM.C | 26 ++++++++++++++++++++++++++
 src/LinAlg/SAM.h |  2 ++
 2 files changed, 28 insertions(+)

diff --git a/src/LinAlg/SAM.C b/src/LinAlg/SAM.C
index 30450306..e49f4aa7 100644
--- a/src/LinAlg/SAM.C
+++ b/src/LinAlg/SAM.C
@@ -720,6 +720,32 @@ bool SAM::getElmEqns (IntVec& meen, int iel, int nedof) const
 }
 
 
+bool SAM::getUniqueEqns (IntSet& meen, int iel) const
+{
+  meen.clear();
+
+  IntVec meenTmp;
+  if (!this->getElmEqns(meenTmp, iel))
+    return false;
+
+  for (int jeq : meenTmp)
+  {
+    if (jeq < 0)
+    {
+      int jpmceq1 = mpmceq[-jeq-1];
+      int jpmceq2 = mpmceq[-jeq]-1;
+      for (int jp = jpmceq1; jp < jpmceq2; ++jp)
+        if (mmceq[jp] > 0)
+          meen.insert(meqn[mmceq[jp]-1]);
+    }
+    else if (jeq != 0)
+      meen.insert(jeq);
+  }
+
+  return true;
+}
+
+
 size_t SAM::getNoElmEqns (int iel) const
 {
   size_t result = 0;
diff --git a/src/LinAlg/SAM.h b/src/LinAlg/SAM.h
index 47daba47..2b1e54c4 100644
--- a/src/LinAlg/SAM.h
+++ b/src/LinAlg/SAM.h
@@ -196,6 +196,8 @@ public:
   //! \brief Returns the number equations for an element.
   //! \param[in] iel Identifier for the element to get number of equations for
   size_t getNoElmEqns(int iel) const;
+  //! \brief Finds the matrix of unique equation numbers for an element.
+  bool getUniqueEqns(IntSet& meen, int iel) const;
 
   //! \brief Finds the matrix of equation numbers for a node.
   //! \param[out] mnen Matrix of node equation numbers