1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * 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 package org.apache.commons.nabla.automatic.functions;
18
19 import org.apache.commons.nabla.automatic.analysis.MethodDifferentiator;
20 import org.objectweb.asm.Opcodes;
21 import org.objectweb.asm.tree.InsnList;
22 import org.objectweb.asm.tree.InsnNode;
23 import org.objectweb.asm.tree.MethodInsnNode;
24
25 /** Differentiation transformer for the acosh function invocation instructions.
26 * <p>As of java 6, the JVM does not supply an inverse hyperbolic
27 * cosine function (see <a
28 * href="http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4919337">bug
29 * 4919337</a>), so this generator will not be triggered for java 6 and below.</p>
30 */
31 public class AcoshTransformer implements MathInvocationTransformer {
32
33 /** {@inheritDoc} */
34 public InsnList getReplacementList(final String owner, final MethodDifferentiator methodDifferentiator) {
35
36 // generate differential code
37 // ... u0, u1 --> ... acosh(u0), u1 / sqrt(u0 * u0 - 1)
38 final InsnList list = new InsnList();
39 list.add(new InsnNode(Opcodes.DUP2_X2));
40 list.add(new InsnNode(Opcodes.POP2));
41 list.add(new InsnNode(Opcodes.DUP2_X2));
42 list.add(new InsnNode(Opcodes.DUP2));
43 list.add(new InsnNode(Opcodes.DMUL));
44 list.add(new InsnNode(Opcodes.DCONST_1));
45 list.add(new InsnNode(Opcodes.DSUB));
46 list.add(new MethodInsnNode(Opcodes.INVOKESTATIC, owner, "sqrt", D_RETURN_D_DESCRIPTOR));
47 list.add(new InsnNode(Opcodes.DDIV));
48 list.add(new InsnNode(Opcodes.DUP2_X2));
49 list.add(new InsnNode(Opcodes.POP2));
50 list.add(new MethodInsnNode(Opcodes.INVOKESTATIC, owner, "acosh", D_RETURN_D_DESCRIPTOR));
51 list.add(new InsnNode(Opcodes.DUP2_X2));
52 list.add(new InsnNode(Opcodes.POP2));
53 return list;
54
55 }
56 }