Mercurial > dive4elements > river
comparison artifacts/src/main/java/org/dive4elements/river/artifacts/math/fitting/LogLinear.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/LogLinear.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 LogLinear | |
4 extends Function | |
5 { | |
6 public static final Derivative DERIVATIVE = | |
7 new Derivative("W'(Q) = a*m/(m*Q + b)") { | |
8 | |
9 @Override | |
10 public org.dive4elements.river.artifacts.math.Function | |
11 instantiate(double [] parameters) | |
12 { | |
13 final double a = parameters[0]; | |
14 final double m = parameters[1]; | |
15 final double b = parameters[2]; | |
16 | |
17 return new org.dive4elements.river.artifacts.math.Function() { | |
18 @Override | |
19 public double value(double Q) { | |
20 return a*m/(m*Q + b); | |
21 } | |
22 }; | |
23 } | |
24 }; | |
25 | |
26 public static final Function INSTANCE = new LogLinear(); | |
27 | |
28 public LogLinear() { | |
29 super( | |
30 "log-linear", | |
31 "W(Q) = a*ln(m*Q + b)", | |
32 new String [] { "a", "m", "b" }); | |
33 } | |
34 | |
35 @Override | |
36 public double value(double x, double [] parameters) { | |
37 return parameters[0]*Math.log(parameters[1]*x + parameters[2]); | |
38 } | |
39 | |
40 @Override | |
41 public double [] gradient(double x, double [] parameters) { | |
42 double a = parameters[0]; | |
43 double m = parameters[1]; | |
44 double b = parameters[2]; | |
45 | |
46 double lin = m*x + b; | |
47 | |
48 return new double [] { | |
49 Math.log(lin), | |
50 a*x / lin, | |
51 a / lin | |
52 }; | |
53 } | |
54 | |
55 @Override | |
56 public Derivative getDerivative() { | |
57 return DERIVATIVE; | |
58 } | |
59 | |
60 @Override | |
61 public Function getInverse() { | |
62 return InvLogLinear.INSTANCE; | |
63 } | |
64 } | |
65 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 : |