teichmann@5831: package org.dive4elements.river.artifacts.math.fitting;
sascha@3177: 
sascha@3177: public class InvLinear
sascha@3177: extends      Function
sascha@3177: {
sascha@3177:     public static Function INSTANCE = new InvLinear();
sascha@3177: 
sascha@3177:     public static final Derivative DERIVATIVE =
sascha@3177:         new Derivative("Q'(W) = 1/m") {
sascha@3177: 
sascha@3177:         @Override
teichmann@5831:         public org.dive4elements.river.artifacts.math.Function
sascha@3177:             instantiate(double [] parameters)
sascha@3177:         {
sascha@3177:             final double _1m = 1d/parameters[0];
sascha@3177: 
teichmann@5831:             return new org.dive4elements.river.artifacts.math.Function() {
sascha@3177:                 @Override
sascha@3177:                 public double value(double Q) {
sascha@3177:                     return _1m;
sascha@3177:                 }
sascha@3177:             };
sascha@3177:         }
sascha@3177:     };
sascha@3177: 
sascha@3177:     public InvLinear() {
sascha@3177:         super("inv-linear", "W(Q) = (Q-b)/m", new String [] { "m", "b" });
sascha@3177:     }
sascha@3177: 
sascha@3177:     @Override
sascha@3177:     public double value(double Q, double [] parameters) {
sascha@3177:         double m = parameters[0];
sascha@3177:         double b = parameters[1];
sascha@3177:         return (Q-b)/m;
sascha@3177:     }
sascha@3177: 
sascha@3177:     @Override
sascha@3177:     public double [] gradient(double Q, double [] parameters) {
sascha@3177:         double m = parameters[0];
sascha@3177:         double b = parameters[1];
sascha@3177:         return new double [] {
sascha@3177:             -(Q-b)/(m*m),
sascha@3177:             -1d/m
sascha@3177:         };
sascha@3177:     }
sascha@3177: 
sascha@3177:     @Override
sascha@3177:     public Derivative getDerivative() {
sascha@3177:         return DERIVATIVE;
sascha@3177:     }
sascha@3177: 
sascha@3177:     @Override
sascha@3177:     public Function getInverse() {
sascha@3177:         return Linear.INSTANCE;
sascha@3177:     }
sascha@3177: }
sascha@3177: // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :