/*
GeoGebra - Dynamic Mathematics for Everyone
http://www.geogebra.org
This file is part of GeoGebra.
This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation.
*/
/*
* Area of polygon P[0], ..., P[n]
*
*/
package org.geogebra.common.kernel.statistics;
import org.geogebra.common.kernel.Construction;
import org.geogebra.common.kernel.algos.AlgoElement;
import org.geogebra.common.kernel.arithmetic.BooleanValue;
import org.geogebra.common.kernel.arithmetic.ExpressionNode;
import org.geogebra.common.kernel.arithmetic.Function;
import org.geogebra.common.kernel.arithmetic.FunctionVariable;
import org.geogebra.common.kernel.commands.Commands;
import org.geogebra.common.kernel.geos.GeoElement;
import org.geogebra.common.kernel.geos.GeoFunction;
import org.geogebra.common.kernel.geos.GeoNumberValue;
/**
* algorithm for Normal[0,1,x]
*
* @author Michael
*/
public class AlgoNormalDF extends AlgoElement implements AlgoDistributionDF {
private GeoNumberValue mean, sd; // input
private BooleanValue cumulative; // optional input
private GeoFunction ret; // output
@SuppressWarnings("javadoc")
public AlgoNormalDF(Construction cons, String label, GeoNumberValue mean,
GeoNumberValue sd, BooleanValue cumulative) {
this(cons, mean, sd, cumulative);
ret.setLabel(label);
}
@SuppressWarnings("javadoc")
public AlgoNormalDF(Construction cons, GeoNumberValue a, GeoNumberValue b,
BooleanValue cumulative) {
super(cons);
this.mean = a;
this.sd = b;
this.cumulative = cumulative;
ret = new GeoFunction(cons);
setInputOutput(); // for AlgoElement
// compute angle
compute();
}
@Override
public Commands getClassName() {
return Commands.Normal;
}
// for AlgoElement
@Override
protected void setInputOutput() {
// dummy function for the "x" argument, eg
// Normal[0,1,x]
// Normal[0,1,x,true]
FunctionVariable fv = new FunctionVariable(kernel);
GeoFunction dummyFun = fv.wrap().buildFunction(fv);
input = new GeoElement[cumulative == null ? 3 : 4];
input[0] = mean.toGeoElement();
input[1] = sd.toGeoElement();
input[2] = dummyFun;
if (cumulative != null) {
input[3] = (GeoElement) cumulative;
}
super.setOutputLength(1);
super.setOutput(0, ret);
setDependencies(); // done by AlgoElement
}
/**
* @return Normal PDF or CDF function
*/
@Override
public GeoFunction getResult() {
return ret;
}
@Override
public void compute() {
FunctionVariable fv = new FunctionVariable(kernel);
ExpressionNode en = new ExpressionNode(kernel, fv);
ExpressionNode div = new ExpressionNode(kernel, sd);
if (cumulative != null && cumulative.getBoolean()) {
ExpressionNode sqrt2 = (new ExpressionNode(kernel, 2)).sqrt();
div = sqrt2.multiply(div.abs());
en = en.subtract(mean).divide(div).erf().plus(1).divide(2);
// old hack from CmdNormal:
// return kernelA.getAlgebraProcessor().processAlgebraCommand(
// "(erf((x-("+mean+"))/(sqrt(2)*abs("+sd+"))) + 1)/2", true );
} else {
ExpressionNode div2 = new ExpressionNode(kernel, sd);
div2 = div2.square().multiply(2);
ExpressionNode sqrt2pi = (new ExpressionNode(kernel, Math.PI))
.multiply(2).sqrt();
div = sqrt2pi.multiply(div.abs());
en = en.subtract(mean).square().reverseSign().divide(div2).exp()
.divide(div);
// old hack:
// return kernelA.getAlgebraProcessor().processAlgebraCommand(
// "exp(-((x-("+mean+"))/("+sd+"))^2/2)/(sqrt(2*pi)*abs("+sd+"))",
// true );
}
Function tempFun = new Function(en, fv);
tempFun.initFunction();
ret.setFunction(tempFun);
}
}