dive4elements/river: flys-artifacts/src/main/java/de/intevation/flys/artifacts/math/LinearRemap.java comparison

First step to calculate "W fuer ungleichwertige Abfluesse" correctly. flys/issue55 flys-artifacts/trunk@1925 c6561f87-3c4e-4783-a992-168aeb5c3f6f

author	Sascha L. Teichmann <sascha.teichmann@intevation.de>
date	Sun, 15 May 2011 21:08:41 +0000
parents
children	343f248e4c8c

comparison

equal deleted inserted replaced

-:c6b7ca0febcb
+:909196be11a0
+package de.intevation.flys.artifacts.math;
+public class LinearRemap
+{
+public static class Segment {
+protected Segment next;
+protected double from;
+protected double to;
+protected double m;
+protected double b;
+public Segment() {
+}
+public Segment(
+double from, double to,
+double m,    double b,
+Segment next
+) {
+this.from = from;
+this.to   = to;
+this.m    = m;
+this.b    = b;
+}
+public double eval(double x) {
+return m*x + b;
+}
+} // class Segment
+protected Segment head;
+public LinearRemap() {
+}
+public void add(
+double from, double to,
+double x1,   double y1,
+double x2,   double y2
+) {
+// y1 = m*x1 + b <=> b = y1 - m*x1
+// y2 = m*x2 + b
+// y2 - y1 = m*(x2 - x1)
+// m = (y2 - y1)/(x2 - x1)
+double m, b;
+if (x2 == x1) {
+m = 0.0;
+b = 0.5*(y2 + y1);
+}
+else {
+m = (y2 - y1)/(x2 - x1);
+b = y1 - m*x1;
+}
+head = new Segment(from, to, m, b, head);
+}
+public double eval(double pos, double x) {
+Segment current = head;
+while (current != null) {
+if (pos >= current.from && pos <= current.to) {
+return current.eval(x);
+}
+current = current.next;
+}
+return Double.NaN;
+}
+}
+// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :

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