/*
* Open Source Physics software is free software as described near the bottom of this code file.
*
* For additional information and documentation on Open Source Physics please see:
* <http://www.opensourcephysics.org/>
*/
package org.opensourcephysics.display2d;
/**
* Title: TestData
* Description: Static methods to generate test data for various programs.
* Copyright: Copyright (c) 2005 Gould, Christian, and Tobochnik
* @author Wolfgang Christian
* @version 1.0
*/
public class TestData {
/**
* Dipole distribution with poles at +1 and -1 on the x axis.
*/
public static double dipole(double x, double y) {
double r1 = Math.sqrt((x-1)*(x-1)+y*y);
double r2 = Math.sqrt((x+1)*(x+1)+y*y);
if((r1==0)||(r2==0)) {
return 0.0; // potential is undefined at r=0.
}
return 1/r1-1/r2;
}
/**
* A 2D Gaussian distribution function centered at x=0 and y=0 and standard deviation of 1.
*/
public static double gaussian(double x, double y, double sigma) {
double rSqr = x*x+y*y;
return Math.exp(-rSqr/sigma/sigma/2);
}
/**
* Saddle function centered at x=0 and y=0.
*/
public static double saddle(double x, double y) {
double rSqr = x*x-y*y;
return Math.exp(rSqr);
}
/**
* Generate a dipole scalar field.
*/
public static double[][][] dipoleScalarField(GridPointData pointdata) {
double[][][] data = pointdata.getData();
for(int i = 0, mx = data.length; i<mx; i++) {
for(int j = 0, my = data[0].length; j<my; j++) {
data[i][j][2] = dipole(data[i][j][0], data[i][j][1]);
}
}
return data;
}
/**
* Generate a gaussian scalar field.
*/
public static double[][][] gaussianScalarField(GridPointData pointdata) {
double[][][] data = pointdata.getData();
for(int i = 0, mx = data.length; i<mx; i++) {
for(int j = 0, my = data[0].length; j<my; j++) {
data[i][j][2] = gaussian(data[i][j][0], data[i][j][1], 1);
}
}
return data;
}
/**
* Generate a random scalar field.
*/
public static void randomScalarField(GridPointData pointdata) {
double[][][] data = pointdata.getData();
for(int i = 0, mx = data.length; i<mx; i++) {
for(int j = 0, my = data[0].length; j<my; j++) {
data[i][j][2] = Math.random();
}
}
}
/**
* Dipole field with poles at +1 and -1 on the x axis. Field strength is
* proportional to 1/r.
*/
public static double[] dipoleVector(double x, double y) {
double[] vec = new double[2];
double r1 = Math.sqrt((x-1)*(x-1)+y*y);
double r2 = Math.sqrt((x+1)*(x+1)+y*y);
if((r1==0)||(r2==0)) {
return vec; // potential is undefined at r=0.
}
vec[0] = (x-1)/r1/r1-(x+1)/r2/r2;
vec[1] = y/r1/r1-y/r2/r2;
return vec;
}
public static double[][][] circulatingVectorField(int nx, int ny) {
double[][][] data = new double[nx][ny][5]; // x, y, horizontal, vertical, color
double xmin = -10, xmax = 10;
double ymin = -10, ymax = 10;
double x = xmin, y = ymin;
double stepx = (xmax-xmin)/(nx-1);
double stepy = (ymax-ymin)/(ny-1);
for(int i = 0; i<nx; i++) {
for(int j = 0; j<ny; j++) {
data[i][j][0] = x; // x location of field calculation
data[i][j][1] = y; // y location of field calculation
double r = Math.sqrt(x*x+y*y);
data[i][j][2] = -y/r; // x length
data[i][j][3] = x/r; // y length
data[i][j][4] = r; // magnitude of the field
y += stepy;
}
y = ymin;
x += stepx;
}
return data;
}
public static double[][][] dipoleVectorField(int nx, int ny, double xmin, double xmax, double ymin, double ymax) {
double[][][] data = new double[nx][ny][5]; // x, y, horizontal, vertical, magnitude
double x = xmin, y = ymin;
double stepx = (xmax-xmin)/(nx-1);
double stepy = (ymax-ymin)/(ny-1);
for(int i = 0; i<nx; i++) {
for(int j = 0; j<ny; j++) {
data[i][j][0] = x; // x location of field calculation
data[i][j][1] = y; // y location of field calculation
double[] vec = dipoleVector(x, y);
double mag = Math.sqrt(vec[0]*vec[0]+vec[1]*vec[1]);
data[i][j][2] = vec[0]/mag; // x direction cosine
data[i][j][3] = vec[1]/mag; // y direction cosine
data[i][j][4] = mag; // magnitude of the field
y += stepy;
}
y = ymin;
x += stepx;
}
return data;
}
}
/*
* Open Source Physics software is free software; you can redistribute
* it and/or modify it under the terms of the GNU General Public License (GPL) as
* published by the Free Software Foundation; either version 2 of the License,
* or(at your option) any later version.
* Code that uses any portion of the code in the org.opensourcephysics package
* or any subpackage (subdirectory) of this package must must also be be released
* under the GNU GPL license.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston MA 02111-1307 USA
* or view the license online at http://www.gnu.org/copyleft/gpl.html
*
* Copyright (c) 2007 The Open Source Physics project
* http://www.opensourcephysics.org
*/