Mercurial > dive4elements > river
comparison flys-artifacts/src/main/java/org/dive4elements/river/artifacts/math/fitting/LogLinear.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/LogLinear.java@59b14bc676ec |
| children |
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| 5830:160f53ee0870 | 5831:bd047b71ab37 |
|---|---|
| 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 : |