From 0b7e825484ab59e61a98b0c724c7f11347b5d5de Mon Sep 17 00:00:00 2001
From: Biljana Bojovic <biljana.bojovic@gmail.com>
Date: Fri, 24 Mar 2023 18:29:26 +0100
Subject: [PATCH] core: Fix MatrixArray multiplication (use the correct matrix
 offset for lhs and rhs matrices)

---
 src/core/model/matrix-array.cc | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/core/model/matrix-array.cc b/src/core/model/matrix-array.cc
index affa42e6a..7ac670ae7 100644
--- a/src/core/model/matrix-array.cc
+++ b/src/core/model/matrix-array.cc
@@ -108,14 +108,16 @@ MatrixArray<T>::operator*(const MatrixArray<T>& rhs) const
 #else // Eigen not found or Eigen optimizations not enabled
 
         size_t matrixOffset = page * m_numRows * m_numCols;
+        size_t rhsMatrixOffset = page * rhs.m_numRows * rhs.m_numCols;
         for (uint16_t i = 0; i < res.m_numRows; ++i)
         {
             for (uint16_t j = 0; j < res.m_numCols; ++j)
             {
-                res(i, j, page) =
-                    (m_values[std::slice(matrixOffset + i, m_numCols, m_numRows)] *
-                     rhs.m_values[std::slice(matrixOffset + j * rhs.m_numRows, rhs.m_numRows, 1)])
-                        .sum();
+                res(i, j, page) = (m_values[std::slice(matrixOffset + i, m_numCols, m_numRows)] *
+                                   rhs.m_values[std::slice(rhsMatrixOffset + j * rhs.m_numRows,
+                                                           rhs.m_numRows,
+                                                           1)])
+                                      .sum();
             }
         }