From 76b51aca761784a7ce41ce9ed7233a99df33d654 Mon Sep 17 00:00:00 2001
From: Antonella Ritorto <anto.ritorto@gmail.com>
Date: Tue, 19 Dec 2023 13:12:30 +0100
Subject: [PATCH] Throw applyAllZMultipliers_ for LGRs

---
 ebos/ecltransmissibility_impl.hh | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/ebos/ecltransmissibility_impl.hh b/ebos/ecltransmissibility_impl.hh
index fa00d36e6..5412c71c9 100644
--- a/ebos/ecltransmissibility_impl.hh
+++ b/ebos/ecltransmissibility_impl.hh
@@ -730,10 +730,20 @@ applyAllZMultipliers_(Scalar& trans,
                       const std::array<int, dimWorld>& cartDims,
                       bool pinchTop)
 {
+    if(grid_.maxLevel()> 0) {
+                OPM_THROW(std::invalid_argument, "MULTZ not support with LGRS, yet.");
+    }
     if (insideFaceIdx > 3) { // top or or bottom
         assert(insideFaceIdx==5); // as insideCartElemIdx < outsideCartElemIdx holds for the Z column
-        assert(outsideCartElemIdx > insideCartElemIdx);
-        auto lastCartElemIdx = outsideCartElemIdx - cartDims[0]*cartDims[1];
+        // For CpGrid with LGRs, insideCartElemIdx == outsideCartElemIdx when cells on the leaf have the same parent cell on level zero.
+        assert(outsideCartElemIdx >= insideCartElemIdx);
+        unsigned lastCartElemIdx;
+        if (outsideCartElemIdx == insideCartElemIdx) {
+            lastCartElemIdx = outsideCartElemIdx;
+        }
+        else {
+            lastCartElemIdx = outsideCartElemIdx - cartDims[0]*cartDims[1];
+        }
         // Last multiplier using (Z+)*(Z-)
         Scalar mult = transMult.getMultiplier(lastCartElemIdx , FaceDir::ZPlus) *
             transMult.getMultiplier(outsideCartElemIdx , FaceDir::ZMinus);