Mercurial > dive4elements > river
view flys-artifacts/src/main/java/de/intevation/flys/artifacts/math/fitting/Exp.java @ 4655:cd44d28d0fbc
Move the access to artifact data to the Access object
Use BedHeightAccess class to receive the data from the artifact. This abstracts
the data access from the actual artifact.
author | Björn Ricks <bjoern.ricks@intevation.de> |
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date | Tue, 11 Dec 2012 09:44:04 +0100 |
parents | 1c00ed73ccf4 |
children |
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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) { double m = parameters[0]; final double a = parameters[1]; final double logam = Math.log(a)*m; return new de.intevation.flys.artifacts.math.Function() { @Override public double value(double Q) { return Math.pow(a, Q)*logam; } }; } }; public static final Function INSTANCE = new Exp(); 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 Q, double [] parameters) { double m = parameters[0]; double a = parameters[1]; double b = parameters[2]; return new double [] { Math.pow(a, Q), Math.pow(a, Q-1d)*m*Q, 1d }; } @Override public Derivative getDerivative() { return DERIVATIVE; } @Override public Function getInverse() { return InvExp.INSTANCE; } } // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :