Index: source/core/tool/interpr1.cxx
===================================================================
--- source/core/tool/interpr1.cxx	(revision 271413)
+++ source/core/tool/interpr1.cxx	(working copy)
@@ -4681,10 +4681,16 @@ void ScInterpreter::ScLookup()
         }
     }
 
+    // For double, string and single reference.
+    double nDataVal;
+    String aDataStr;
+    bool bValueData = false;
+
     // Get the data-result range and also determine whether this is vertical
     // lookup or horizontal lookup.
 
-    switch (GetStackType())
+    StackVar eDataArrayType = GetStackType();
+    switch (eDataArrayType)
     {
         case svDoubleRef:
         {
@@ -4714,6 +4720,36 @@ void ScInterpreter::ScLookup()
             nLenMajor = bVertical ? nR : nC;
         }
         break;
+        case svDouble:
+        {
+            nDataVal = GetDouble();
+            bValueData = true;
+        }
+        break;
+        case svString:
+        {
+            aDataStr = GetString();
+        }
+        break;
+        case svSingleRef:
+        {
+            ScAddress aDataAdr;
+            PopSingleRef( aDataAdr );
+            const ScBaseCell* pDataCell = GetCell( aDataAdr );
+            if ( HasCellValueData( pDataCell ) )
+            {
+                nDataVal = GetCellValue( aDataAdr, pDataCell );
+                bValueData = true;
+            }
+            else if ( GetCellType( pDataCell ) == CELLTYPE_NONE )
+            {
+                nDataVal = 0.0;
+                bValueData = true;
+            }
+            else
+                GetCellString( aDataStr, pDataCell );
+        }
+        break;
         default:
             PushIllegalParameter();
             return;
@@ -4733,6 +4769,66 @@ void ScInterpreter::ScLookup()
     if ( !FillEntry(rEntry) )
         return;
 
+    if ( eDataArrayType == svDouble || eDataArrayType == svString
+            || eDataArrayType == svSingleRef )
+    {
+        // Delta position for a single value is always 0.
+
+        // Found if data <= query, but not if query is string and found data is 
+        // numeric or vice versa. This is how Excel does it but doesn't 
+        // document it.
+
+        bool bFound = false;
+        if ( bValueData )
+        {
+            if ( rEntry.bQueryByString )
+                bFound = false;
+            else
+                bFound = (nDataVal <= rEntry.nVal);
+        }
+        else
+        {
+            if ( !rEntry.bQueryByString )
+                bFound = false;
+            else
+            {
+                sal_Int32 nCompare = ScGlobal::pCollator->compareString(
+                                         aDataStr, *rEntry.pStr );
+                bFound = (nCompare <= 0);
+            }
+        }
+
+        if (!bFound)
+        {
+            PushNA();
+            return;
+        }
+
+        if (pResMat)
+        {
+            if (pResMat->IsValue( 0 ))
+                PushDouble(pResMat->GetDouble( 0 ));
+            else
+                PushString(pResMat->GetString( 0 ));
+        }
+        else if (nParamCount == 3)
+        {
+            ScAddress aAdr;
+            aAdr.SetTab( nResTab);
+            aAdr.SetCol( nResCol1);
+            aAdr.SetRow( nResRow1);
+            PushCellResultToken( true, aAdr, NULL, NULL);
+        }
+        else
+        {
+            if ( bValueData )
+                PushDouble( nDataVal );
+            else
+                PushString( aDataStr );
+        }
+        return;
+    }
+
     // Now, perform the search to compute the delta position (nDelta).
 
     if (pDataMat)
@@ -4818,6 +4914,20 @@ void ScInterpreter::ScLookup()
             bFound = true;
         }
 
+        // With 0-9 < A-Z, if query is numeric and data found is string, or 
+        // vice versa, the (yet another undocumented) Excel behavior is to 
+        // return #N/A instead.
+
+        if (bFound)
+        {
+            SCCOLROW i = nDelta;
+            SCSIZE n = pDataMat->GetElementCount();
+            if (static_cast<SCSIZE>(i) >= n)
+                i = static_cast<SCCOLROW>(n);
+            if (bool(rEntry.bQueryByString) == bool(pDataMat->IsValue(i)))
+                bFound = false;
+        }
+
         if (!bFound)
         {
             PushNA();
Index: source/core/tool/parclass.cxx
===================================================================
--- source/core/tool/parclass.cxx	(revision 269325)
+++ source/core/tool/parclass.cxx	(working copy)
@@ -130,7 +130,7 @@ const ScParameterClassification::RawData ScParamet
     { ocLarge,           {{ Reference, Value                       },   false }},
     { ocLess,            {{ Array, Array                           },   false }},
     { ocLessEqual,       {{ Array, Array                           },   false }},
-    { ocLookup,          {{ Value, Reference, Reference            },   false }},
+    { ocLookup,          {{ Value, ForceArray, ForceArray          },   false }},
     { ocMatch,           {{ Value, Reference, Reference            },   false }},
     { ocMatDet,          {{ ForceArray                             },   false }},
     { ocMatInv,          {{ ForceArray                             },   false }},