Minor improvements to fault calculations

ApplicationCode/ReservoirDataModel/RigGridBase.cpp

@@ -216,6 +216,25 @@ bool RigGridBase::ijkFromCellIndex( size_t cellIndex, size_t* i, size_t* j, size
     return true;
 }
 
+//--------------------------------------------------------------------------------------------------
+/// This version does no if-guarding. Check that all dimensions of the grid are non-zero before using.
+/// Useful for running in a loop after doing the sanity check once.
+//--------------------------------------------------------------------------------------------------
+void RigGridBase::ijkFromCellIndexNonGuarded( size_t cellIndex, size_t* i, size_t* j, size_t* k ) const
+{
+    size_t index = cellIndex;
+
+    size_t cellCountI = m_gridPointDimensions[0] - 1;
+    size_t cellCountJ = m_gridPointDimensions[1] - 1;
+    size_t cellCountK = m_gridPointDimensions[2] - 1;
+
+    *k = index / ( cellCountI * cellCountJ );
+    index -= ( *k ) * ( cellCountI * cellCountJ );
+    *j = index / cellCountI;
+    index -= ( *j ) * cellCountI;
+    *i = index;
+}
+
 //--------------------------------------------------------------------------------------------------
 ///
 //--------------------------------------------------------------------------------------------------