Mercurial > dive4elements > river
diff flys-artifacts/src/main/java/de/intevation/flys/artifacts/math/fitting/InvLinear.java @ 3177:585c0b49e696
Added inverses of the fitting functions.
flys-artifacts/trunk@4792 c6561f87-3c4e-4783-a992-168aeb5c3f6f
author | Sascha L. Teichmann <sascha.teichmann@intevation.de> |
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date | Tue, 26 Jun 2012 06:33:37 +0000 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/flys-artifacts/src/main/java/de/intevation/flys/artifacts/math/fitting/InvLinear.java Tue Jun 26 06:33:37 2012 +0000 @@ -0,0 +1,57 @@ +package de.intevation.flys.artifacts.math.fitting; + +public class InvLinear +extends Function +{ + public static Function INSTANCE = new InvLinear(); + + public static final Derivative DERIVATIVE = + new Derivative("Q'(W) = 1/m") { + + @Override + public de.intevation.flys.artifacts.math.Function + instantiate(double [] parameters) + { + final double _1m = 1d/parameters[0]; + + return new de.intevation.flys.artifacts.math.Function() { + @Override + public double value(double Q) { + return _1m; + } + }; + } + }; + + public InvLinear() { + super("inv-linear", "W(Q) = (Q-b)/m", new String [] { "m", "b" }); + } + + @Override + public double value(double Q, double [] parameters) { + double m = parameters[0]; + double b = parameters[1]; + return (Q-b)/m; + } + + @Override + public double [] gradient(double Q, double [] parameters) { + double m = parameters[0]; + double b = parameters[1]; + return new double [] { + -(Q-b)/(m*m), + -1d/m + }; + } + + @Override + public Derivative getDerivative() { + return DERIVATIVE; + } + + @Override + public Function getInverse() { + return Linear.INSTANCE; + } +} +// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :