package com.smartmap.algorithm.equation.differential.partial.ellipsoidal;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.OutputStream;

import java.io.StringWriter;

public class PoissonIteration {

public static void main(String[] args) {

int m = 64; int n = 32;

double minX = 0;

double maxX = 2;

double dx = (maxX - minX) / m;

double minY = 0;

double maxY = 1;

double dy = (maxY - minY) / n;

//

double xx[][] = new double[m+1][n+1];

//

System.out.println("----------------------------------------");

for(int j=0; j<m+1; j++)

{

double value = dx * j;

System.out.print(value + " ");

}

System.out.println("");

System.out.println("----------------------------------------");

for(int j=0; j<n+1; j++)

{

double value = dy * j;

System.out.print(value + " ");

}

System.out.println("");

//

for(int j=0; j<n+1; j++)

{

double value = dy * j;

xx[0][j] = getZeroXU(value);

xx[m][j] = getTwoXU(value);

}

for(int k=0; k<m+1; k++)

{

double value = dx * k;

xx[k][0] = getZeroYU(value);

xx[k][n] = getOneYU(value);

}

double error;

while(true)

{

error = gaussSeidelCompute(xx, m, n, dx, dy);

System.out.println("error: "+error);

if(error < 0.00000000001)

{

break;

}

}

System.out.println("--------------------------------");

for(int k=0; k<n+1; k++)

{

for(int j=0; j<m+1; j++)

{

System.out.printf(" %8.6f", xx[j][k]);

}

System.out.println(";");

}

}

public static double gaussSeidelCompute(double[][] xx, int m, int n, double dx, double dy)

{

double dxdy = (1.0/Math.pow(dy, 2) + 1.0/Math.pow(dx, 2)) * 2;

double error = 0;

for(int i=1; i<m; i++)

{

for(int j=1; j<n; j++)

{

double oldValue = xx[i][j];

double x = 0 + dx * i;

double y = 0 + dy * j;

double f = getF(x, y);

xx[i][j] = (f + xx[i][j-1]*(1.0/Math.pow(dy, 2)) + xx[i-1][j]*(1.0/Math.pow(dx, 2)) + xx[i+1][j]*(1.0/Math.pow(dx, 2)) + xx[i][j+1]*(1.0/Math.pow(dy, 2)));

xx[i][j] = xx[i][j] / dxdy;

oldValue = Math.abs(xx[i][j] - oldValue);

if(oldValue > error)

error = oldValue;

}

}

return error;

}

    public static void outputAA(double[][] aa, int elementCount, String filePath, String fileName)

    {

try

{

FileOutputStream fileStream = new FileOutputStream(filePath + "\\"+fileName+".txt", false);

OutputStream outputStream = fileStream;

StringWriter streamWriter=new StringWriter();

for(int j=0; j<elementCount; j++)

{

for(int k=0; k<elementCount; k++)

{

streamWriter.write(String.format(" %8.6f", aa[j][k]));

}

streamWriter.write("\n");

}

       char[] linearRingStringCharArray = streamWriter.toString().toCharArray();

       for(int i=0; i<linearRingStringCharArray.length; i++)

       {

        outputStream.write(linearRingStringCharArray[i]);

       }

       fileStream.close();

streamWriter.close();

} catch (IOException e) {

e.printStackTrace();

}

}

public static double getF(double x, double y)

{

double returnValue = 0;

returnValue = (Math.pow(Math.PI, 2) - 1) * Math.exp(x) * Math.sin(Math.PI * y);

return returnValue;

}

public static double getZeroXU(double y)

{

double returnValue = 0;

returnValue = Math.sin(Math.PI * y);

return returnValue;

}

public static double getTwoXU(double y)

{

double returnValue = 0;

returnValue = Math.exp(2) * Math.sin(Math.PI * y);

return returnValue;

}

public static double getZeroYU(double y)

{

double returnValue = 0;

return returnValue;

}

public static double getOneYU(double y)

{

double returnValue = 0;

return returnValue;

}

}