Mercurial > dive4elements > river
diff flys-artifacts/src/main/java/org/dive4elements/river/artifacts/math/fitting/InvPow.java @ 5831:bd047b71ab37
Repaired internal references
author | Sascha L. Teichmann <teichmann@intevation.de> |
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date | Thu, 25 Apr 2013 12:06:39 +0200 |
parents | flys-artifacts/src/main/java/de/intevation/flys/artifacts/math/fitting/InvPow.java@de67497de5a0 |
children |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/flys-artifacts/src/main/java/org/dive4elements/river/artifacts/math/fitting/InvPow.java Thu Apr 25 12:06:39 2013 +0200 @@ -0,0 +1,72 @@ +package org.dive4elements.river.artifacts.math.fitting; + +public class InvPow +extends Function +{ + public static final Derivative DERIVATIVE = + new Derivative("Q'(W) = ((W-d)/a)^(1/c)/(c*(W-d))") { + + @Override + public org.dive4elements.river.artifacts.math.Function + instantiate(double [] parameters) + { + double a = parameters[0]; + final double c = parameters[1]; + final double d = parameters[2]; + final double _1a = 1d/a; + final double _1c = 1d/c; + + return new org.dive4elements.river.artifacts.math.Function() { + @Override + public double value(double W) { + double Wd = W-d; + return Math.pow(Wd*_1a, _1c)/(c*Wd); + } + }; + } + }; + + public static final Function INSTANCE = new InvPow(); + + public InvPow() { + super( + "pow", + "Q(W) = ((W-d)/a)^(1/c)", + new String [] { "a", "c", "d" }); + } + + @Override + public double value(double W, double [] parameters) { + double a = parameters[0]; + double c = parameters[1]; + double d = parameters[2]; + return Math.pow((W-d)/a, 1d/c); + } + + @Override + public double [] gradient(double W, double [] parameters) { + double a = parameters[0]; + double c = parameters[1]; + double d = parameters[2]; + double _1c = 1d/c; + double Wdac = Math.pow((W-d)/a, 1d/c); + double Wd = W-d; + return new double [] { + -Wdac/(a*c), + (Wdac*Math.log(Wd/a))/(c*c), + -Wdac/(c*Wd) + }; + } + + @Override + public Derivative getDerivative() { + // TODO: Implement me! + return null; + } + + @Override + public Function getInverse() { + return Pow.INSTANCE; + } +} +// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :