Index: src/org/apache/poi/ss/formula/atp/TestPercentile.java
===================================================================
--- src/org/apache/poi/ss/formula/atp/TestPercentile.java	(revision 0)
+++ src/org/apache/poi/ss/formula/atp/TestPercentile.java	(revision 0)
@@ -0,0 +1,112 @@
+/* ====================================================================
+   Licensed to the Apache Software Foundation (ASF) under one or more
+   contributor license agreements.  See the NOTICE file distributed with
+   this work for additional information regarding copyright ownership.
+   The ASF licenses this file to You under the Apache License, Version 2.0
+   (the "License"); you may not use this file except in compliance with
+   the License.  You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+==================================================================== */
+package org.apache.poi.ss.formula.atp;
+
+import org.apache.poi.ss.formula.eval.AreaEval;
+import org.apache.poi.ss.formula.eval.BlankEval;
+import org.apache.poi.ss.formula.eval.BoolEval;
+import org.apache.poi.ss.formula.eval.ErrorEval;
+import org.apache.poi.ss.formula.eval.NumberEval;
+import org.apache.poi.ss.formula.eval.ValueEval;
+import org.apache.poi.ss.formula.functions.AggregateFunction;
+import org.apache.poi.ss.formula.functions.EvalFactory;
+
+import junit.framework.TestCase;
+
+/**
+ * Testcase for Excel function PERCENTILE()
+ * 
+ * @author T. Gordon
+ */
+public class TestPercentile extends TestCase {
+
+	public void testPercentile() {
+		testBasic();
+		testUnusualArgs();
+		testUnusualArgs2();
+		testUnusualArgs3();
+		testErrors();
+		testErrors2();
+	}
+
+	private static ValueEval invokePercentile(ValueEval[] args, ValueEval percentile) {
+		AreaEval aeA = EvalFactory.createAreaEval("A1:A" + args.length, args);
+		ValueEval[] args2 = { aeA, percentile };
+		return AggregateFunction.PERCENTILE.evaluate(args2, -1, -1);
+	}
+
+	private void confirmPercentile(ValueEval percentile, ValueEval[] args, double expected) {
+		ValueEval result = invokePercentile(args, percentile);
+		assertEquals(NumberEval.class, result.getClass());
+		double delta = 0.00000001;
+		assertEquals(expected, ((NumberEval) result).getNumberValue(), delta);
+	}
+
+	private void confirmPercentile(ValueEval percentile, ValueEval[] args, ErrorEval expectedError) {
+		ValueEval result = invokePercentile(args, percentile);
+		assertEquals(ErrorEval.class, result.getClass());
+		assertEquals(expectedError.getErrorCode(), ((ErrorEval) result).getErrorCode());
+	}
+
+	public void testBasic() {
+		ValueEval[] values = { new NumberEval(210.128), new NumberEval(65.2182), new NumberEval(32.231),
+				new NumberEval(12.123), new NumberEval(45.32) };
+		ValueEval percentile = new NumberEval(0.95);
+		confirmPercentile(percentile, values, 181.14604);
+	}
+
+	public void testBlanks() {
+		ValueEval[] values = { new NumberEval(210.128), new NumberEval(65.2182), new NumberEval(32.231),
+				BlankEval.instance, new NumberEval(45.32) };
+		ValueEval percentile = new NumberEval(0.95);
+		confirmPercentile(percentile, values, 188.39153);
+	}
+
+	public void testUnusualArgs() {
+		ValueEval[] values = { new NumberEval(1), new NumberEval(2), BoolEval.TRUE, BoolEval.FALSE };
+		ValueEval percentile = new NumberEval(0.95);
+		confirmPercentile(percentile, values, 1.95);
+	}
+
+	//percentile has to be between 0 and 1 - here we test less than zero
+	public void testUnusualArgs2() {
+		ValueEval[] values = { new NumberEval(1), new NumberEval(2), };
+		ValueEval percentile = new NumberEval(-0.1);
+		confirmPercentile(percentile, values, ErrorEval.NUM_ERROR);
+	}
+
+	//percentile has to be between 0 and 1 - here we test more than 1
+	public void testUnusualArgs3() {
+		ValueEval[] values = { new NumberEval(1), new NumberEval(2) };
+		ValueEval percentile = new NumberEval(1.1);
+		confirmPercentile(percentile, values, ErrorEval.NUM_ERROR);
+	}
+
+	//here we test where there are errors as part of inputs
+	public void testErrors() {
+		ValueEval[] values = { new NumberEval(1), ErrorEval.NAME_INVALID, new NumberEval(3), ErrorEval.DIV_ZERO, };
+		ValueEval percentile = new NumberEval(0.95);
+		confirmPercentile(percentile, values, ErrorEval.NAME_INVALID);
+	}
+
+	//here we test where there are errors as part of inputs
+	public void testErrors2() {
+		ValueEval[] values = { new NumberEval(1), new NumberEval(2), new NumberEval(3), ErrorEval.DIV_ZERO, };
+		ValueEval percentile = new NumberEval(0.95);
+		confirmPercentile(percentile, values, ErrorEval.DIV_ZERO);
+	}
+}