diff --git a/src/scratchpad/src/org/apache/poi/hssf/record/formula/functions/Not.java b/src/scratchpad/src/org/apache/poi/hssf/record/formula/functions/Not.java
index 65893f5fb..0d8519d2e 100644
--- a/src/scratchpad/src/org/apache/poi/hssf/record/formula/functions/Not.java
+++ b/src/scratchpad/src/org/apache/poi/hssf/record/formula/functions/Not.java
@@ -4,11 +4,104 @@
  */
 package org.apache.poi.hssf.record.formula.functions;
 
+import org.apache.poi.hssf.record.formula.eval.AreaEval;
+import org.apache.poi.hssf.record.formula.eval.BlankEval;
+import org.apache.poi.hssf.record.formula.eval.BoolEval;
+import org.apache.poi.hssf.record.formula.eval.ErrorEval;
+import org.apache.poi.hssf.record.formula.eval.Eval;
+import org.apache.poi.hssf.record.formula.eval.NumberEval;
+import org.apache.poi.hssf.record.formula.eval.RefEval;
+import org.apache.poi.hssf.record.formula.eval.StringEval;
+import org.apache.poi.hssf.record.formula.eval.ValueEval;
+
 
 /**
- * @author
- *  
+ * @author Amol S. Deshmukh < amol at apache dot org >
+ * The NOT boolean function. Returns negation of specified value
+ * (treated as a boolean). If the specified arg is a number,
+ * then it is true <=> 'number is non-zero'
  */
-public class Not extends DefaultFunctionImpl {
-
+public class Not extends BooleanFunction {
+    
+  
+    public Eval evaluate(Eval[] operands, int srcRow, short srcCol) {
+        ValueEval retval = null;
+        boolean b = true;
+        ValueEval tempVe = null;
+        
+        switch (operands.length) {
+        default:
+            retval = ErrorEval.VALUE_INVALID;
+            break;
+        case 1:
+            if (operands[0] instanceof AreaEval) {
+                AreaEval ae = (AreaEval) operands[0];
+                if (ae.isRow() && ae.containsColumn(srcCol)) {
+                    ValueEval ve = ae.getValueAt(ae.getFirstRow(), srcCol);
+                    tempVe = singleOperandEvaluate(ve);
+                } else if (ae.isColumn() && ae.containsRow(srcRow)) {
+                    ValueEval ve = ae.getValueAt(srcRow, ae.getFirstColumn());
+                    tempVe = singleOperandEvaluate(ve);
+                } else {
+                    retval = ErrorEval.VALUE_INVALID;
+                }            
+            }
+            else {
+                tempVe = singleOperandEvaluate(operands[0]);
+                if (tempVe instanceof StringEval) {
+                    retval = ErrorEval.VALUE_INVALID;
+                }
+                else if (tempVe instanceof ErrorEval) {
+                    retval = tempVe;
+                }
+            }
+        }
+        
+        if (retval == null) { // if no error
+            if (tempVe instanceof BoolEval) {
+                b = b && ((BoolEval) tempVe).getBooleanValue();
+            }
+            else if (tempVe instanceof StringEval) {
+                retval = ErrorEval.VALUE_INVALID;
+            }
+            else if (tempVe instanceof ErrorEval) {
+                retval = tempVe;
+            }
+            retval = b ? BoolEval.FALSE : BoolEval.TRUE;
+        }
+        
+        return retval;
+    }
+    
+    
+    protected ValueEval singleOperandEvaluate(Eval ve) {
+        ValueEval retval = ErrorEval.VALUE_INVALID;
+        if (ve instanceof RefEval) {
+            RefEval re = (RefEval) ve;
+            retval = singleOperandEvaluate(re.getInnerValueEval());
+        }
+        else if (ve instanceof BoolEval) {
+            retval = (BoolEval) ve;
+        }
+        else if (ve instanceof NumberEval) {
+            NumberEval ne = (NumberEval) ve;
+            retval = ne.getNumberValue() != 0 ? BoolEval.TRUE : BoolEval.FALSE;
+        }
+        else if (ve instanceof StringEval) {
+            StringEval se = (StringEval) ve;
+            String str = se.getStringValue();
+            retval = str.equalsIgnoreCase("true")
+                    ? BoolEval.TRUE
+                    : str.equalsIgnoreCase("false")
+                            ? BoolEval.FALSE
+                            : (ValueEval) ErrorEval.VALUE_INVALID;
+        }
+        else if (ve instanceof BlankEval) {
+            retval = BoolEval.FALSE;
+        }
+        else {
+            retval = ErrorEval.VALUE_INVALID;
+        }
+        return retval;
+    }
 }