Mercurial > dive4elements > river
view flys-artifacts/src/main/java/de/intevation/flys/artifacts/math/Linear.java @ 4496:d8992459b408
Add method to return the facets of an artifact
This methos should be used to get the facets of an artifact instead of accessing
the facets member variable directly.
author | Björn Ricks <bjoern.ricks@intevation.de> |
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date | Wed, 14 Nov 2012 11:11:04 +0100 |
parents | da1969b05292 |
children |
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package de.intevation.flys.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 :