Mercurial > dive4elements > river
view artifacts/src/main/java/org/dive4elements/river/artifacts/math/Linear.java @ 8755:30b1ddadf275
(issue1801) Unify reference gauge finding code
The basic way as described in the method comment of the
determineRefGauge method is now used in the WINFOArtifact,
MainValuesService and RiverUtils.getGauge method.
RiverUtils.getGauge previously just returned the first
gauge found. While this is now a behavior change I believe
that it is always more correct then the undeterministic
behavior of the previous implmenentation.
author | Andre Heinecke <andre.heinecke@intevation.de> |
---|---|
date | Wed, 24 Jun 2015 14:07:26 +0200 |
parents | af13ceeba52a |
children |
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/* Copyright (C) 2011, 2012, 2013 by Bundesanstalt für Gewässerkunde * Software engineering by Intevation GmbH * * This file is Free Software under the GNU AGPL (>=v3) * and comes with ABSOLUTELY NO WARRANTY! Check out the * documentation coming with Dive4Elements River for details. */ package org.dive4elements.river.artifacts.math; public final class Linear implements Function { private double m; private double b; public Linear( double x1, double x2, double y1, double y2 ) { // y1 = m*x1 + b // y2 = m*x2 + b // y2 - y1 = m*(x2 - x1) // m = (y2 - y1)/(x2 - x1) # x2 != x1 // b = y1 - m*x1 if (x1 == x2) { m = 0; b = 0.5*(y1 + y2); } else { m = (y2 - y1)/(x2 - x1); b = y1 - m*x1; } } public static final double linear( double x, double x1, double x2, double y1, double y2 ) { // y1 = m*x1 + b // y2 = m*x2 + b // y2 - y1 = m*(x2 - x1) // m = (y2 - y1)/(x2 - x1) # x2 != x1 // b = y1 - m*x1 if (x1 == x2) { return 0.5*(y1 + y2); } double m = (y2 - y1)/(x2 - x1); double b = y1 - m*x1; return x*m + b; } @Override public double value(double x) { return m*x + b; } public static final double factor(double x, double p1, double p2) { // 0 = m*p1 + b <=> b = -m*p1 // 1 = m*p2 + b // 1 = m*(p2 - p1) // m = 1/(p2 - p1) # p1 != p2 // f(x) = x/(p2-p1) - p1/(p2-p1) <=> (x-p1)/(p2-p1) return p1 == p2 ? 0.0 : (x-p1)/(p2-p1); } public static final double weight(double factor, double a, double b) { //return (1.0-factor)*a + factor*b; return a + factor*(b-a); } public static final void weight( double factor, double [] a, double [] b, double [] c ) { int N = Math.min(Math.min(a.length, b.length), c.length); for (int i = 0; i < N; ++i) { c[i] = weight(factor, a[i], b[i]); } } } // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :