Mercurial > dive4elements > river
view flys-artifacts/src/main/java/de/intevation/flys/artifacts/math/fitting/InvLogLinear.java @ 3181:de67497de5a0
Completed inverse functions.
flys-artifacts/trunk@4796 c6561f87-3c4e-4783-a992-168aeb5c3f6f
author | Sascha L. Teichmann <sascha.teichmann@intevation.de> |
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date | Tue, 26 Jun 2012 10:54:12 +0000 |
parents | 59b14bc676ec |
children |
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package de.intevation.flys.artifacts.math.fitting; public class InvLogLinear extends Function { public static final Derivative DERIVATIVE = new Derivative("Q'(W) = e^(W/a)/(a*m)") { @Override public de.intevation.flys.artifacts.math.Function instantiate(double [] parameters) { final double _1a = 1d/parameters[0]; final double _1am = 1d/(parameters[0] * parameters[1]); return new de.intevation.flys.artifacts.math.Function() { @Override public double value(double W) { return Math.exp(W*_1a)*_1am; } }; } }; public static final Function INSTANCE = new InvLogLinear(); public InvLogLinear() { super( "inv-log-linear", "Q(W)=(e^(W/a)-b)/m", new String [] { "a", "m", "b" }); } @Override public double value(double W, double [] parameters) { double a = parameters[0]; double m = parameters[1]; double b = parameters[2]; return (Math.exp(W/a) - b)/m; } @Override public double [] gradient(double W, double [] parameters) { double a = parameters[0]; double m = parameters[1]; double b = parameters[2]; double eWa = Math.exp(W/a); return new double [] { -(W*eWa)/(a*a*m) -(eWa-b)/(m*m), -1/m }; } @Override public Derivative getDerivative() { return DERIVATIVE; } @Override public Function getInverse() { return LogLinear.INSTANCE; } } // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :