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