Mercurial > dive4elements > river
view flys-artifacts/src/main/java/de/intevation/flys/artifacts/math/fitting/InvExp.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 | 585c0b49e696 |
children |
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package de.intevation.flys.artifacts.math.fitting; public class InvExp extends Function { public static final Derivative DERIVATIVE = new Derivative("W'(Q) = 1/(log(a)*(Q-b))") { @Override public de.intevation.flys.artifacts.math.Function instantiate(double [] parameters) { final double a = parameters[1]; final double b = parameters[2]; final double loga = Math.log(a); return new de.intevation.flys.artifacts.math.Function() { @Override public double value(double Q) { return 1d/(loga*(Q-a)); } }; } }; public static final Function INSTANCE = new InvExp(); public InvExp() { super( "inv-exp", "Q(W) = log((W-b)/m)/log(a)", new String [] { "m", "a", "b" }); } @Override public double value(double W, double [] parameters) { double m = parameters[0]; double a = parameters[1]; double b = parameters[2]; return Math.log((W-b)/m)/Math.log(a); } @Override public double [] gradient(double Q, double [] parameters) { double m = parameters[0]; double a = parameters[1]; double b = parameters[2]; double loga = Math.log(a); return new double [] { -1d/(loga*m), -Math.log((Q-b)/m)/(a*loga*loga), -1d/(loga*(Q-b)) }; } @Override public Derivative getDerivative() { return DERIVATIVE; } @Override public Function getInverse() { return Exp.INSTANCE; } } // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :