#1593 Fixed an issue with MATCH function when range is sorted in descending order (#1594)

Author: swmal

src/EPPlus/FormulaParsing/Excel/Functions/RefAndLookup/LookupUtils/LookupBinarySearch.cs

@@ -139,6 +139,12 @@ internal static int BinarySearch(object lookupValue, IRangeInfo lookupRange, boo
             return asc ? SearchAsc(lookupValue, lookupRange, comparer, direction) : SearchDesc(lookupValue, lookupRange, comparer);
         }
 
+        internal static int GetMaxIndex(IRangeInfo returnArray)
+        {
+            return returnArray.Size.NumberOfRows > returnArray.Size.NumberOfCols ?
+                    returnArray.Size.NumberOfRows : returnArray.Size.NumberOfCols;
+        }
+
         internal static int GetMatchIndex(int ix, IRangeInfo returnArray, LookupMatchMode matchMode, bool asc)
         {
             if (ix > -1) return ix;
@@ -150,9 +156,8 @@ internal static int GetMatchIndex(int ix, IRangeInfo returnArray, LookupMatchMod
             else if (matchMode == LookupMatchMode.ExactMatchReturnNextLarger)
             {
                 var adjustment = asc ? 0 : -1;
-                var max = returnArray.Size.NumberOfRows > returnArray.Size.NumberOfCols ?
-                    returnArray.Size.NumberOfRows : returnArray.Size.NumberOfCols;
-                result = result >= max ? result : result + adjustment;
+                var max = GetMaxIndex(returnArray);
+                result = result >= max ? max : result + adjustment;
             }
             return result;
         }

src/EPPlus/FormulaParsing/Excel/Functions/RefAndLookup/Match.cs

@@ -64,7 +64,8 @@ public override CompileResult Execute(IList<FunctionArgument> arguments, Parsing
             {
                 return CompileResult.GetErrorResult(eErrorType.NA);
             }
-            return CreateResult(index + 1, DataType.Integer);
+            var max = LookupBinarySearch.GetMaxIndex(lookupRange);
+            return CreateResult(index >= max ? index : index + 1, DataType.Integer);
         }
 		/// <summary>
 		/// If the function is allowed in a pivot table calculated field

src/EPPlusTest/FormulaParsing/Excel/Functions/RefAndLookup/MatchTests.cs

@@ -134,5 +134,37 @@ public void MatchShouldWorkWithSingleCell()
 
             Assert.AreEqual(1, formulaCell.GetValue<int>());
         }
+
+        [TestMethod]
+        public void MatchTest_GreaterThanOrEqual_ShouldReturnIndexOfLast()
+        {
+            _worksheet.Cells["G3"].Value = 1d;
+            _worksheet.Cells["G4"].Value = 0.75;
+            _worksheet.Cells["G5"].Value = 0.5;
+            _worksheet.Cells["G6"].Value = 0.27;
+            _worksheet.Cells["G7"].Value = 0.1;
+
+            _worksheet.Cells["A1"].Formula = "MATCH(0.01,G3:G7,-1)";
+
+            _worksheet.Calculate();
+
+            Assert.AreEqual(5, _worksheet.Cells["A1"].Value);
+        }
+
+        [TestMethod]
+        public void MatchTest_GreaterThanOrEqual_ShouldReturnIndexOfSecondLast()
+        {
+            _worksheet.Cells["G3"].Value = 1d;
+            _worksheet.Cells["G4"].Value = 0.75;
+            _worksheet.Cells["G5"].Value = 0.5;
+            _worksheet.Cells["G6"].Value = 0.27;
+            _worksheet.Cells["G7"].Value = 0.1;
+
+            _worksheet.Cells["A1"].Formula = "MATCH(0.11,G3:G7,-1)";
+
+            _worksheet.Calculate();
+
+            Assert.AreEqual(4, _worksheet.Cells["A1"].Value);
+        }
     }
 }