Mercurial > dive4elements > river
comparison flys-artifacts/src/main/java/de/intevation/flys/artifacts/math/fitting/SQPow.java @ 3100:c0abfb695332
SQ: Add new power function.
flys-artifacts/trunk@4699 c6561f87-3c4e-4783-a992-168aeb5c3f6f
| author | Sascha L. Teichmann <sascha.teichmann@intevation.de> |
|---|---|
| date | Tue, 19 Jun 2012 11:13:04 +0000 |
| parents | |
| children | 6391ca82141c |
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| 3099:ef0dd585b5e0 | 3100:c0abfb695332 |
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| 1 package de.intevation.flys.artifacts.math.fitting; | |
| 2 | |
| 3 public class SQPow | |
| 4 extends Function | |
| 5 { | |
| 6 public static final Derivative DERIVATIVE = | |
| 7 new Derivative("W'(Q) = a*b*Q^(b-1)") { | |
| 8 | |
| 9 @Override | |
| 10 public de.intevation.flys.artifacts.math.Function | |
| 11 instantiate(double [] parameters) | |
| 12 { | |
| 13 final double a = parameters[0]; | |
| 14 final double b = parameters[1]; | |
| 15 | |
| 16 return new de.intevation.flys.artifacts.math.Function() { | |
| 17 @Override | |
| 18 public double value(double Q) { | |
| 19 return a*b*Math.pow(Q, b-1); | |
| 20 } | |
| 21 }; | |
| 22 } | |
| 23 }; | |
| 24 | |
| 25 public SQPow() { | |
| 26 super( | |
| 27 "sq-pow", | |
| 28 "S(Q) = a*Q^b", | |
| 29 new String [] { "a", "b" }); | |
| 30 } | |
| 31 | |
| 32 @Override | |
| 33 public double value(double x, double [] parameters) { | |
| 34 return parameters[0]*Math.pow(x, parameters[1]); | |
| 35 } | |
| 36 | |
| 37 @Override | |
| 38 public double [] gradient(double q, double [] parameters) { | |
| 39 double a = parameters[0]; | |
| 40 double b = parameters[1]; | |
| 41 double q_b = Math.pow(q, b); | |
| 42 return new double [] { | |
| 43 q_b, | |
| 44 a*q_b*Math.log(q), | |
| 45 }; | |
| 46 } | |
| 47 | |
| 48 @Override | |
| 49 public Derivative getDerivative() { | |
| 50 return DERIVATIVE; | |
| 51 } | |
| 52 } | |
| 53 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 : |