实现逆矩阵的算法！

[zjhlht]

应为要做hill体制的算法~~~~~~

所以在这里求java的逆矩阵算法！

谢谢了~~~

[bigzhangsong]

Guass消去算法，应该可以吧？可以参考《高等代数》

[zzr82528]

希望下面的代码可以帮上忙

package cn.zzr.test;

public class Matrix {

	double[][] a = { { 0.0, 2.0, 0.0, 1.0 }, { 2.0, 2.0, 3.0, 2.0 },
			{ 4.0, -3.0, 0.0, 1.0 }, { 6.0, 1.0, -6.0, -5.0 } };



	int anrow = 4;
	double[] vv = new double[anrow];
	int[] indx = new int[anrow];

	private void lucmp() {
		int n = anrow, imax = 0;
		for (int i = 0; i < n; i++) {
			double big = 0.0;
			for (int j = 0; j < n; j++) {
				double temp = Math.abs(a[i][j]);
				if (temp > big)
					big = temp;
			}
			vv[i] = 1.0 / big;
		}
		for (int j = 0; j < n; j++) {
			for (int i = 0; i < j; i++) {
				double sum = a[i][j];
				for (int k = 0; k < i; k++)
					sum -= a[i][k] * a[k][j];
				a[i][j] = sum;
			}
			double big = 0.0;
			for (int i = j; i < n; i++) {
				double sum = a[i][j];
				for (int k = 0; k < j; k++)
					sum -= a[i][k] * a[k][j];
				a[i][j] = sum;
				double dum = vv[i] * Math.abs(sum);
				if (dum >= big) {
					big = dum;
					imax = i;
				}
			}
			if (j != imax) {
				for (int i = 0; i < n; i++) {
					double mid = a[imax][i];
					a[imax][i] = a[j][i];
					a[j][i] = mid;
				}
				double mid = vv[j];
				vv[j] = vv[imax];
				vv[imax] = mid;
			}
			indx[j] = imax;
			if (j != n - 1) {
				double dum = 1.0 / a[j][j];
				for (int i = j + 1; i < n; i++)
					a[i][j] *= dum;
			}
		}
	}

	private void lubksb(double[] b) {
		int n = anrow, ii = 0;
		// y
		for (int i = 0; i < n; i++) {
			int ip = indx[i];
			double sum = b[ip];
			b[ip] = b[i];
			if (ii != 0)
				for (int j = ii - 1; j < i; j++)
					sum -= a[i][j] * b[j];
			else
				ii = i + 1;
			b[i] = sum;
		}
		// x
		for (int i = n - 1; i >= 0; i--) {
			double sum = b[i];
			for (int j = i + 1; j < n; j++)
				sum -= a[i][j] * b[j];
			b[i] = sum / a[i][i];
		}
	}

	private void output(double a[][], int anrow) {
		for (int i = 0; i < anrow; i++) {
			System.out.println(" | " + a[i][0] + " " + a[i][1] + " " + a[i][2]
					+ " " + a[i][3] + " | ");
		}
	}

	public Matrix() {
		System.out.println("Origin matrix:");
		output(a, 4);
		lucmp();
		double[] b = new double[anrow];
		double[][] y = new double[anrow][anrow];
		for (int i = 0; i < anrow; i++) {
			for (int j = 0; j < anrow; j++)
				b[j] = 0;
			b[i] = 1.0;
			lubksb(b);
			for (int j = 0; j < anrow; j++)
				y[j][i] = b[j];
		}
		System.out.println("Its inverse matrix:");
		output(y, 4);
	}

	public static void main(String[] args) {
		new Matrix();
	}

}

[zjhlht]

楼上的代码好像在哪见过~~~~~~~

呵呵~~~~

不过还是非常感谢~~~~~

先研究研究！！！！

[ninesea]

矩阵的逆忘了