Mercurial > dive4elements > gnv-client
comparison gnv-artifacts/src/main/java/de/intevation/gnv/math/LinearFunction.java @ 657:af3f56758f59
merged gnv-artifacts/0.5
| author | Thomas Arendsen Hein <thomas@intevation.de> |
|---|---|
| date | Fri, 28 Sep 2012 12:13:53 +0200 |
| parents | d9d933e06875 |
| children | 9a828e5a2390 |
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| 590:5f5f273c8566 | 657:af3f56758f59 |
|---|---|
| 1 package de.intevation.gnv.math; | |
| 2 | |
| 3 import org.apache.commons.math.optimization.fitting.ParametricRealFunction; | |
| 4 | |
| 5 import org.apache.commons.math.FunctionEvaluationException; | |
| 6 | |
| 7 import org.apache.commons.math.analysis.UnivariateRealFunction; | |
| 8 | |
| 9 /** | |
| 10 * @author Sascha L. Teichmann (sascha.teichmann@intevation.de) | |
| 11 */ | |
| 12 public class LinearFunction | |
| 13 implements ParametricRealFunction | |
| 14 { | |
| 15 public static final LinearFunction INSTANCE = new LinearFunction(); | |
| 16 | |
| 17 public static class Univariate | |
| 18 implements UnivariateRealFunction | |
| 19 { | |
| 20 protected double m; | |
| 21 protected double b; | |
| 22 | |
| 23 public Univariate() { | |
| 24 } | |
| 25 | |
| 26 public Univariate(double x1, double y1, double x2, double y2) { | |
| 27 if (y1 == y2) { | |
| 28 m = 0d; | |
| 29 b = (x1 + x2)*0.5d; | |
| 30 } | |
| 31 else { | |
| 32 m = (x1 - x2)/(y1 - y2); | |
| 33 b = y1 - m*x1; | |
| 34 } | |
| 35 } | |
| 36 | |
| 37 public double value(double x) { | |
| 38 return m*x + b; | |
| 39 } | |
| 40 } // class Univariate | |
| 41 | |
| 42 public LinearFunction() { | |
| 43 } | |
| 44 | |
| 45 public double value(double x, double [] parameters) | |
| 46 throws FunctionEvaluationException | |
| 47 { | |
| 48 return x*parameters[0] + parameters[1]; | |
| 49 } | |
| 50 | |
| 51 public double [] gradient(double x, double [] parameters) | |
| 52 throws FunctionEvaluationException | |
| 53 { | |
| 54 return new double [] { x, 1f }; | |
| 55 } | |
| 56 } | |
| 57 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 : |