Mercurial > dive4elements > river
comparison flys-artifacts/src/main/java/org/dive4elements/river/artifacts/math/fitting/InvLogLinear.java @ 5831:bd047b71ab37
Repaired internal references
| author | Sascha L. Teichmann <teichmann@intevation.de> |
|---|---|
| date | Thu, 25 Apr 2013 12:06:39 +0200 |
| parents | flys-artifacts/src/main/java/de/intevation/flys/artifacts/math/fitting/InvLogLinear.java@de67497de5a0 |
| children |
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| 5830:160f53ee0870 | 5831:bd047b71ab37 |
|---|---|
| 1 package org.dive4elements.river.artifacts.math.fitting; | |
| 2 | |
| 3 public class InvLogLinear | |
| 4 extends Function | |
| 5 { | |
| 6 public static final Derivative DERIVATIVE = | |
| 7 new Derivative("Q'(W) = e^(W/a)/(a*m)") { | |
| 8 | |
| 9 @Override | |
| 10 public org.dive4elements.river.artifacts.math.Function | |
| 11 instantiate(double [] parameters) | |
| 12 { | |
| 13 final double _1a = 1d/parameters[0]; | |
| 14 final double _1am = 1d/(parameters[0] * parameters[1]); | |
| 15 | |
| 16 return new org.dive4elements.river.artifacts.math.Function() { | |
| 17 @Override | |
| 18 public double value(double W) { | |
| 19 return Math.exp(W*_1a)*_1am; | |
| 20 } | |
| 21 }; | |
| 22 } | |
| 23 }; | |
| 24 public static final Function INSTANCE = new InvLogLinear(); | |
| 25 | |
| 26 public InvLogLinear() { | |
| 27 super( | |
| 28 "inv-log-linear", | |
| 29 "Q(W)=(e^(W/a)-b)/m", | |
| 30 new String [] { "a", "m", "b" }); | |
| 31 } | |
| 32 | |
| 33 @Override | |
| 34 public double value(double W, double [] parameters) { | |
| 35 double a = parameters[0]; | |
| 36 double m = parameters[1]; | |
| 37 double b = parameters[2]; | |
| 38 return (Math.exp(W/a) - b)/m; | |
| 39 } | |
| 40 | |
| 41 @Override | |
| 42 public double [] gradient(double W, double [] parameters) { | |
| 43 double a = parameters[0]; | |
| 44 double m = parameters[1]; | |
| 45 double b = parameters[2]; | |
| 46 double eWa = Math.exp(W/a); | |
| 47 return new double [] { | |
| 48 -(W*eWa)/(a*a*m) | |
| 49 -(eWa-b)/(m*m), | |
| 50 -1/m | |
| 51 }; | |
| 52 } | |
| 53 | |
| 54 @Override | |
| 55 public Derivative getDerivative() { | |
| 56 return DERIVATIVE; | |
| 57 } | |
| 58 | |
| 59 @Override | |
| 60 public Function getInverse() { | |
| 61 return LogLinear.INSTANCE; | |
| 62 } | |
| 63 } | |
| 64 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 : |