Mercurial > dive4elements > river
comparison artifacts/src/main/java/org/dive4elements/river/artifacts/math/fitting/InvQuad.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/InvQuad.java@bd047b71ab37 |
| children | 4897a58c8746 |
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| 5837:d9901a08d0a6 | 5838:5aa05a7a34b7 |
|---|---|
| 1 package org.dive4elements.river.artifacts.math.fitting; | |
| 2 | |
| 3 public class InvQuad | |
| 4 extends Function | |
| 5 { | |
| 6 public static final Derivative DERIVATIVE = | |
| 7 new Derivative("Q'(W) = 1/sqrt(4*n*(W-b)+m^2)") { | |
| 8 | |
| 9 @Override | |
| 10 public org.dive4elements.river.artifacts.math.Function | |
| 11 instantiate(double [] parameters) | |
| 12 { | |
| 13 double n = parameters[0]; | |
| 14 double m = parameters[1]; | |
| 15 final double b = parameters[2]; | |
| 16 final double n4 = 4d*n; | |
| 17 final double mm = m*m; | |
| 18 | |
| 19 return new org.dive4elements.river.artifacts.math.Function() { | |
| 20 @Override | |
| 21 public double value(double W) { | |
| 22 return 1d/Math.sqrt(n4*(W-b)+mm); | |
| 23 } | |
| 24 }; | |
| 25 } | |
| 26 }; | |
| 27 | |
| 28 public static final Function INSTANCE = new InvQuad(); | |
| 29 | |
| 30 public InvQuad() { | |
| 31 super( | |
| 32 "inv-quad", | |
| 33 "(sqrt(4*n*W-4*b*n+m^2)-m)/(2*n)", | |
| 34 new String [] { "n", "m", "b" }); | |
| 35 } | |
| 36 | |
| 37 @Override | |
| 38 public double value(double W, double [] parameters) { | |
| 39 double n = parameters[0]; | |
| 40 double m = parameters[1]; | |
| 41 double b = parameters[2]; | |
| 42 return (Math.sqrt(4d*n*(W - b) + m*m)-m)/(2d*n); | |
| 43 } | |
| 44 | |
| 45 @Override | |
| 46 public double [] gradient(double W, double [] parameters) { | |
| 47 double n = parameters[0]; | |
| 48 double m = parameters[1]; | |
| 49 double b = parameters[2]; | |
| 50 double Wb = W-b; | |
| 51 double sn4Wb = Math.sqrt(4d*n*Wb + m*m); | |
| 52 return new double [] { | |
| 53 Wb/(n*sn4Wb)-(sn4Wb-m)/(2d*n*n), | |
| 54 (m/sn4Wb-1d)/(2d*n), | |
| 55 -1d/sn4Wb | |
| 56 }; | |
| 57 } | |
| 58 | |
| 59 @Override | |
| 60 public Derivative getDerivative() { | |
| 61 return DERIVATIVE; | |
| 62 } | |
| 63 | |
| 64 @Override | |
| 65 public Function getInverse() { | |
| 66 return Quad.INSTANCE; | |
| 67 } | |
| 68 } | |
| 69 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 : |