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annotate flys-artifacts/src/main/java/de/intevation/flys/artifacts/math/fitting/SQPow.java @ 3177:585c0b49e696

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Added inverses of the fitting functions. flys-artifacts/trunk@4792 c6561f87-3c4e-4783-a992-168aeb5c3f6f
author Sascha L. Teichmann <sascha.teichmann@intevation.de>
date Tue, 26 Jun 2012 06:33:37 +0000
parents 6391ca82141c
children 59b14bc676ec
rev   line source
3100
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Sascha L. Teichmann <sascha.teichmann@intevation.de>
parents:
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1 package de.intevation.flys.artifacts.math.fitting;
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2
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3 public class SQPow
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4 extends Function
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5 {
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6 public static final Derivative DERIVATIVE =
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7 new Derivative("S'(Q) = a*b*Q^(b-1)") {
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8
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9 @Override
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10 public de.intevation.flys.artifacts.math.Function
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11 instantiate(double [] parameters)
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12 {
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13 final double a = parameters[0];
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14 final double b = parameters[1];
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15
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16 return new de.intevation.flys.artifacts.math.Function() {
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17 @Override
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18 public double value(double Q) {
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19 return a*b*Math.pow(Q, b-1);
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20 }
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21 };
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22 }
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23 };
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24
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25 public SQPow() {
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26 super(
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27 "sq-pow",
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28 "S(Q) = a*Q^b",
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29 new String [] { "a", "b" });
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30 }
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31
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32 @Override
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33 public double value(double x, double [] parameters) {
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34 return parameters[0]*Math.pow(x, parameters[1]);
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35 }
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36
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37 @Override
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38 public double [] gradient(double q, double [] parameters) {
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39 double a = parameters[0];
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40 double b = parameters[1];
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41 double q_b = Math.pow(q, b);
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42 return new double [] {
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43 q_b,
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44 a*q_b*Math.log(q),
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45 };
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46 }
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47
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48 @Override
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49 public Derivative getDerivative() {
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50 return DERIVATIVE;
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51 }
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52
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53 @Override
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54 public Function getInverse() {
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55 return InvSQPow.INSTANCE;
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56 }
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57 }
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58 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :
http://dive4elements.wald.intevation.org