Mercurial > dive4elements > river
comparison flys-artifacts/src/main/java/org/dive4elements/river/artifacts/math/fitting/InvSQPow.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/InvSQPow.java@de67497de5a0 |
| children |
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| 5830:160f53ee0870 | 5831:bd047b71ab37 |
|---|---|
| 1 package org.dive4elements.river.artifacts.math.fitting; | |
| 2 | |
| 3 public class InvSQPow | |
| 4 extends Function | |
| 5 { | |
| 6 public static final Derivative DERIVATIVE = | |
| 7 new Derivative("Q'(S) = (S/a)^(1/b)/(b*S)") { | |
| 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 b = parameters[1]; | |
| 15 final double _1b = 1d/b; | |
| 16 | |
| 17 return new org.dive4elements.river.artifacts.math.Function() { | |
| 18 @Override | |
| 19 public double value(double S) { | |
| 20 return Math.pow(S*_1a, _1b)/(b*S); | |
| 21 } | |
| 22 }; | |
| 23 } | |
| 24 }; | |
| 25 public static final Function INSTANCE = new InvSQPow(); | |
| 26 | |
| 27 public InvSQPow() { | |
| 28 super( | |
| 29 "inv-sq-pow", | |
| 30 "Q(S) = Q=(S/a)^(1/b)", | |
| 31 new String [] { "a", "b" }); | |
| 32 } | |
| 33 | |
| 34 @Override | |
| 35 public double value(double S, double [] parameters) { | |
| 36 double a = parameters[0]; | |
| 37 double b = parameters[1]; | |
| 38 return Math.pow(S/a, 1d/b); | |
| 39 } | |
| 40 | |
| 41 @Override | |
| 42 public double [] gradient(double S, double [] parameters) { | |
| 43 double a = parameters[0]; | |
| 44 double b = parameters[1]; | |
| 45 double Sa = S/a; | |
| 46 double _1b = 1d/b; | |
| 47 double eSa1b = Math.pow(Sa, _1b); | |
| 48 return new double [] { | |
| 49 -eSa1b/(a*b), | |
| 50 -(eSa1b*Math.log(Sa))/(b*b) | |
| 51 }; | |
| 52 } | |
| 53 | |
| 54 @Override | |
| 55 public Derivative getDerivative() { | |
| 56 return DERIVATIVE; | |
| 57 } | |
| 58 | |
| 59 @Override | |
| 60 public Function getInverse() { | |
| 61 return SQPow.INSTANCE; | |
| 62 } | |
| 63 } | |
| 64 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 : |