Mercurial > dive4elements > river
diff artifacts/src/main/java/org/dive4elements/river/artifacts/math/fitting/InvLog.java @ 5838:5aa05a7a34b7
Rename modules to more fitting names.
author | Sascha L. Teichmann <teichmann@intevation.de> |
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date | Thu, 25 Apr 2013 15:23:37 +0200 |
parents | flys-artifacts/src/main/java/org/dive4elements/river/artifacts/math/fitting/InvLog.java@bd047b71ab37 |
children | 4897a58c8746 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/artifacts/src/main/java/org/dive4elements/river/artifacts/math/fitting/InvLog.java Thu Apr 25 15:23:37 2013 +0200 @@ -0,0 +1,55 @@ +package org.dive4elements.river.artifacts.math.fitting; + +public class InvLog +extends Function +{ + public static final Derivative DERIVATIVE = + new Derivative("Q'(W) = exp(W/m)/m") { + + @Override + public org.dive4elements.river.artifacts.math.Function + instantiate(double [] parameters) + { + final double _1m = 1d / parameters[0]; + + return new org.dive4elements.river.artifacts.math.Function() { + @Override + public double value(double W) { + return Math.exp(W*_1m)*_1m; + } + }; + } + }; + + public static final Function INSTANCE = new InvLog(); + + public InvLog() { + super("inv-log", "Q(W) = e^(W/m) - b", new String [] { "m", "b" }); + } + + @Override + public double value(double w, double [] parameters) { + double m = parameters[0]; + double b = parameters[1]; + return Math.exp(w/m) - b; + } + + @Override + public double [] gradient(double w, double [] parameters) { + double m = parameters[0]; + double b = parameters[1]; + double ewm = Math.exp(w/m); + return new double [] { -w*ewm/(m*m), -1 }; + } + + @Override + public Derivative getDerivative() { + return DERIVATIVE; + } + + @Override + public Function getInverse() { + return Log.INSTANCE; + } +} +// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :