Mercurial > dive4elements > river
diff flys-artifacts/src/main/java/org/dive4elements/river/artifacts/math/fitting/Log.java @ 5831:bd047b71ab37
Repaired internal references
author | Sascha L. Teichmann <teichmann@intevation.de> |
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date | Thu, 25 Apr 2013 12:06:39 +0200 |
parents | flys-artifacts/src/main/java/de/intevation/flys/artifacts/math/fitting/Log.java@585c0b49e696 |
children |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/flys-artifacts/src/main/java/org/dive4elements/river/artifacts/math/fitting/Log.java Thu Apr 25 12:06:39 2013 +0200 @@ -0,0 +1,57 @@ +package org.dive4elements.river.artifacts.math.fitting; + +public class Log +extends Function +{ + public static final Derivative DERIVATIVE = + new Derivative("W'(Q) = m/(Q+b)") { + + @Override + public org.dive4elements.river.artifacts.math.Function + instantiate(double [] parameters) + { + final double m = parameters[0]; + final double b = parameters[1]; + + return new org.dive4elements.river.artifacts.math.Function() { + @Override + public double value(double Q) { + return m/(Q+b); + } + }; + } + }; + + public static final Function INSTANCE = new Log(); + + public Log() { + super("log", "W(Q) = m*ln(Q + b)", new String [] { "m", "b" }); + } + + @Override + public double value(double x, double [] parameters) { + return parameters[0]*Math.log(x + parameters[1]); + } + + @Override + public double [] gradient(double x, double [] parameters) { + double m = parameters[0]; + double b = parameters[1]; + double b_x = b + x; + return new double [] { + Math.log(b_x), + m/b_x + }; + } + + @Override + public Derivative getDerivative() { + return DERIVATIVE; + } + + @Override + public Function getInverse() { + return InvLog.INSTANCE; + } +} +// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :