Mercurial > dive4elements > river
view flys-artifacts/src/main/java/de/intevation/flys/artifacts/math/fitting/InvSQPow.java @ 3736:da1969b05292
WST tables: Added interpolation of tabulated values only.
flys-artifacts/trunk@5411 c6561f87-3c4e-4783-a992-168aeb5c3f6f
author | Sascha L. Teichmann <sascha.teichmann@intevation.de> |
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date | Sun, 09 Sep 2012 15:29:06 +0000 |
parents | de67497de5a0 |
children |
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package de.intevation.flys.artifacts.math.fitting; public class InvSQPow extends Function { public static final Derivative DERIVATIVE = new Derivative("Q'(S) = (S/a)^(1/b)/(b*S)") { @Override public de.intevation.flys.artifacts.math.Function instantiate(double [] parameters) { final double _1a = 1d/parameters[0]; final double b = parameters[1]; final double _1b = 1d/b; return new de.intevation.flys.artifacts.math.Function() { @Override public double value(double S) { return Math.pow(S*_1a, _1b)/(b*S); } }; } }; public static final Function INSTANCE = new InvSQPow(); public InvSQPow() { super( "inv-sq-pow", "Q(S) = Q=(S/a)^(1/b)", new String [] { "a", "b" }); } @Override public double value(double S, double [] parameters) { double a = parameters[0]; double b = parameters[1]; return Math.pow(S/a, 1d/b); } @Override public double [] gradient(double S, double [] parameters) { double a = parameters[0]; double b = parameters[1]; double Sa = S/a; double _1b = 1d/b; double eSa1b = Math.pow(Sa, _1b); return new double [] { -eSa1b/(a*b), -(eSa1b*Math.log(Sa))/(b*b) }; } @Override public Derivative getDerivative() { return DERIVATIVE; } @Override public Function getInverse() { return SQPow.INSTANCE; } } // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :