Mercurial > dive4elements > river
view flys-artifacts/src/main/java/de/intevation/flys/artifacts/math/fitting/Exp.java @ 3009:4dda67a893da
FixA: Added the derivatives of all fitting functions.
flys-artifacts/trunk@4565 c6561f87-3c4e-4783-a992-168aeb5c3f6f
author | Sascha L. Teichmann <sascha.teichmann@intevation.de> |
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date | Thu, 31 May 2012 16:32:03 +0000 |
parents | 0dd58ab7e118 |
children | 585c0b49e696 |
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package de.intevation.flys.artifacts.math.fitting; public class Exp extends Function { public static final Derivative DERIVATIVE = new Derivative("W'(Q) = a^Q*log(a)*m") { @Override public de.intevation.flys.artifacts.math.Function instantiate(double [] parameters) { final double m = parameters[0]; final double a = parameters[1]; return new de.intevation.flys.artifacts.math.Function() { @Override public double value(double Q) { return Math.pow(a, Q)*Math.log(a)*m; } }; } }; public Exp() { super( "exp", "W(Q) = m * a^Q + b", new String [] { "m", "a", "b" }); } @Override public double value(double x, double [] parameters) { return parameters[0]*Math.pow(parameters[1], x) + parameters[2]; } @Override public double [] gradient(double x, double [] parameters) { return new double [] { Math.pow(parameters[1], x), Math.pow(parameters[1], x-1d)*x, 1d }; } @Override public Derivative getDerivative() { return DERIVATIVE; } } // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :