public class Gauss {
	private double matrix[];
	private int cols, rows;

	public void makeMatrix(int r, int c) {
		cols = c;
		rows = r;
		matrix = new double[c * r];
	}

	public double getValue(int r, int c) {
		return matrix[r * cols + c];
	}

	public void setValue(int r, int c, double v) {
		matrix[r * cols + c] = v;
	}

	public void dumpMatrix() {
		int i, j;

		System.out.println("---");
		for (i = 0; i < rows; i++) {
			for (j = 0; j < cols; j++) {
				System.out.print(getValue(i, j) + " ");
			}
			System.out.println("");
		}
	}

	int findrow(int n) {
		int i;

		for (i = n; i < rows; i++) {
			if (getValue(i, n) != 0)
				break;
		}
		if (i >= rows)
			i = -1;
		if (i != n) {
			System.out.println("ha!");
		}
		return i;
	}

	void swaprows(int a, int b) {
		double x;
		int i;

		for(i = 0; i < cols; i++) {
			x = getValue(a, i);	
			setValue(a, i, getValue(b, i));
			setValue(b, i, x);
		}
	}

	public void addRow(int row, double[] d) {
		int i;

		for (i = 0; i < cols; i++)
			setValue(row, i, d[i]);
	}

	public double[] Eliminate() {
		int i, j, k;
		double[] ret = new double[rows];
		for (i = 0; i < rows; i++) {
			double t1;
			int t4;

			t4 = findrow(i);	
			if (t4 == -1) {
				continue;
			}

			if (t4 != i) {
				swaprows(t4, i);
			}

			t1 = getValue(i, i);

			for (j = i; j < cols; j++) {
				setValue(i, j, getValue(i, j)/t1);
			}

			for (j = i + 1; j < rows; j++) {
				double t2;

				t2 = getValue(j, i);
				for (k=i; k < cols; k++) {
					setValue(j, k, getValue(j, k)-t2*getValue(i, k));
				}
			}
		}

		for (i = rows - 1; i >= 0; i--) {
			if (getValue(i, i) == 0) {
				for (j = i + 1; j < cols; j++) {
					if (getValue(i, j) == 0) {
						break;
					}
				}
				if (j != cols)
						break;
			}
			for (j = i - 1; j >= 0; j--) {
				double t3;

				t3 = getValue(j, i);

				for (k = i; k < cols; k++) {
					setValue(j, k, getValue(j, k) - t3*getValue(i, k));
				}
			}
		}

		for (i = 0; i < rows; i++)
			ret[i] = getValue(i, cols-1);

		return ret;
	
	}

}