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140package 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; } }
转载于:https://www.cnblogs.com/gispathfinder/p/5770063.html
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