01: /*
02: * Licensed to the Apache Software Foundation (ASF) under one or more
03: * contributor license agreements. See the NOTICE file distributed with
04: * this work for additional information regarding copyright ownership.
05: * The ASF licenses this file to You under the Apache License, Version 2.0
06: * (the "License"); you may not use this file except in compliance with
07: * the License. You may obtain a copy of the License at
08: *
09: * http://www.apache.org/licenses/LICENSE-2.0
10: *
11: * Unless required by applicable law or agreed to in writing, software
12: * distributed under the License is distributed on an "AS IS" BASIS,
13: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14: * See the License for the specific language governing permissions and
15: * limitations under the License.
16: */
17: /*
18: * Created on May 6, 2005
19: *
20: */
21: package org.apache.poi.hssf.record.formula.functions;
22:
23: import org.apache.poi.hssf.record.formula.eval.BlankEval;
24: import org.apache.poi.hssf.record.formula.eval.ErrorEval;
25: import org.apache.poi.hssf.record.formula.eval.Eval;
26: import org.apache.poi.hssf.record.formula.eval.NumberEval;
27: import org.apache.poi.hssf.record.formula.eval.NumericValueEval;
28: import org.apache.poi.hssf.record.formula.eval.ValueEval;
29:
30: /**
31: * @author Amol S. Deshmukh < amolweb at ya hoo dot com >
32: * Support for hyperbolic trig functions was added as a part of
33: * Java distribution only in JDK1.5. This class uses custom
34: * naive implementation based on formulas at:
35: * http://www.math2.org/math/trig/hyperbolics.htm
36: * These formulas seem to agree with excel's implementation.
37: *
38: */
39: public class Atanh extends NumericFunction {
40:
41: public Eval evaluate(Eval[] operands, int srcRow, short srcCol) {
42: double d = 0;
43: ValueEval retval = null;
44:
45: switch (operands.length) {
46: default:
47: retval = ErrorEval.VALUE_INVALID;
48: break;
49: case 1:
50: ValueEval ve = singleOperandEvaluate(operands[0], srcRow,
51: srcCol);
52: if (ve instanceof NumericValueEval) {
53: NumericValueEval ne = (NumericValueEval) ve;
54: d = ne.getNumberValue();
55: } else if (ve instanceof BlankEval) {
56: // do nothing
57: } else {
58: retval = ErrorEval.NUM_ERROR;
59: }
60: }
61:
62: if (retval == null) {
63: d = MathX.atanh(d);
64: retval = (Double.isNaN(d) || Double.isInfinite(d)) ? (ValueEval) ErrorEval.NUM_ERROR
65: : new NumberEval(d);
66: }
67: return retval;
68: }
69:
70: }
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