Mercurial > dive4elements > river
comparison artifacts/src/main/java/org/dive4elements/river/artifacts/math/fitting/InvPow.java @ 5838:5aa05a7a34b7
Rename modules to more fitting names.
author | Sascha L. Teichmann <teichmann@intevation.de> |
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date | Thu, 25 Apr 2013 15:23:37 +0200 |
parents | flys-artifacts/src/main/java/org/dive4elements/river/artifacts/math/fitting/InvPow.java@bd047b71ab37 |
children | 4897a58c8746 |
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5837:d9901a08d0a6 | 5838:5aa05a7a34b7 |
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1 package org.dive4elements.river.artifacts.math.fitting; | |
2 | |
3 public class InvPow | |
4 extends Function | |
5 { | |
6 public static final Derivative DERIVATIVE = | |
7 new Derivative("Q'(W) = ((W-d)/a)^(1/c)/(c*(W-d))") { | |
8 | |
9 @Override | |
10 public org.dive4elements.river.artifacts.math.Function | |
11 instantiate(double [] parameters) | |
12 { | |
13 double a = parameters[0]; | |
14 final double c = parameters[1]; | |
15 final double d = parameters[2]; | |
16 final double _1a = 1d/a; | |
17 final double _1c = 1d/c; | |
18 | |
19 return new org.dive4elements.river.artifacts.math.Function() { | |
20 @Override | |
21 public double value(double W) { | |
22 double Wd = W-d; | |
23 return Math.pow(Wd*_1a, _1c)/(c*Wd); | |
24 } | |
25 }; | |
26 } | |
27 }; | |
28 | |
29 public static final Function INSTANCE = new InvPow(); | |
30 | |
31 public InvPow() { | |
32 super( | |
33 "pow", | |
34 "Q(W) = ((W-d)/a)^(1/c)", | |
35 new String [] { "a", "c", "d" }); | |
36 } | |
37 | |
38 @Override | |
39 public double value(double W, double [] parameters) { | |
40 double a = parameters[0]; | |
41 double c = parameters[1]; | |
42 double d = parameters[2]; | |
43 return Math.pow((W-d)/a, 1d/c); | |
44 } | |
45 | |
46 @Override | |
47 public double [] gradient(double W, double [] parameters) { | |
48 double a = parameters[0]; | |
49 double c = parameters[1]; | |
50 double d = parameters[2]; | |
51 double _1c = 1d/c; | |
52 double Wdac = Math.pow((W-d)/a, 1d/c); | |
53 double Wd = W-d; | |
54 return new double [] { | |
55 -Wdac/(a*c), | |
56 (Wdac*Math.log(Wd/a))/(c*c), | |
57 -Wdac/(c*Wd) | |
58 }; | |
59 } | |
60 | |
61 @Override | |
62 public Derivative getDerivative() { | |
63 // TODO: Implement me! | |
64 return null; | |
65 } | |
66 | |
67 @Override | |
68 public Function getInverse() { | |
69 return Pow.INSTANCE; | |
70 } | |
71 } | |
72 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 : |