1 /*
2 * Licensed to the Hipparchus project 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 Hipparchus project 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 * https://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.hipparchus.special.elliptic.jacobi;
18
19 import org.hipparchus.CalculusFieldElement;
20 import org.hipparchus.util.FastMath;
21
22 /** Algorithm for computing the principal Jacobi functions for negative parameter m.
23 * <p>
24 * The rules for negative parameter change are given in Abramowitz and Stegun, section 16.10.
25 * </p>
26 * @param <T> the type of the field elements
27 * @since 2.0
28 */
29 class FieldNegativeParameter<T extends CalculusFieldElement<T>> extends FieldJacobiElliptic<T> {
30
31 /** Algorithm to use for the positive parameter. */
32 private final FieldJacobiElliptic<T> algorithm;
33
34 /** Input scaling factor. */
35 private final T inputScale;
36
37 /** output scaling factor. */
38 private final T outputScale;
39
40 /** Simple constructor.
41 * @param m parameter of the Jacobi elliptic function (must be negative here)
42 */
43 FieldNegativeParameter(final T m) {
44 super(m);
45 final T omM = m.getField().getOne().subtract(m);
46 algorithm = JacobiEllipticBuilder.build(m.negate().divide(omM));
47 inputScale = FastMath.sqrt(omM);
48 outputScale = inputScale.reciprocal();
49 }
50
51 /** {@inheritDoc} */
52 @Override
53 public FieldCopolarN<T> valuesN(final T u) {
54 final FieldCopolarD<T> trioD = new FieldCopolarD<>(algorithm.valuesN(u.multiply(inputScale)));
55 return new FieldCopolarN<>(outputScale.multiply(trioD.sd()), trioD.cd(), trioD.nd());
56 }
57
58 }