Mercurial > dive4elements > river
view artifacts/src/main/java/org/dive4elements/river/artifacts/math/fitting/Pow.java @ 5863:4897a58c8746
River artifacts: Added new copyright headers.
author | Sascha L. Teichmann <teichmann@intevation.de> |
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date | Sun, 28 Apr 2013 14:40:59 +0200 |
parents | 5aa05a7a34b7 |
children | af13ceeba52a |
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/* Copyright (C) 2011, 2012, 2013 by Bundesanstalt für Gewässerkunde * Software engineering by Intevation GmbH * * This file is Free Software under the GNU AGPL (>=v3) * and comes with ABSOLUTELY NO WARRANTY! Check out the * documentation coming with Dive4Elements River for details. */ package org.dive4elements.river.artifacts.math.fitting; public class Pow extends Function { public static final Derivative DERIVATIVE = new Derivative("W'(Q) = a*c*Q^(c-1)") { @Override public org.dive4elements.river.artifacts.math.Function instantiate(double [] parameters) { final double a = parameters[0]; final double c = parameters[1]; return new org.dive4elements.river.artifacts.math.Function() { @Override public double value(double Q) { return a*c*Math.pow(Q, c-1); } }; } }; public static final Function INSTANCE = new Pow(); public Pow() { super( "pow", "W(Q) = a*Q^c + d", new String [] { "a", "c", "d" }); } @Override public double value(double x, double [] parameters) { return parameters[0]*Math.pow(x, parameters[1]) + parameters[2]; } @Override public double [] gradient(double x, double [] parameters) { double a = parameters[0]; double c = parameters[1]; double x_c = Math.pow(x, c); return new double [] { x_c, a*x_c*Math.log(x), 1d }; } @Override public Derivative getDerivative() { return DERIVATIVE; } @Override public Function getInverse() { return InvPow.INSTANCE; } } // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :