Ajuda métodos - matriz

public class Matrix3D {
	public double[][] a = new double[3][3];

	Matrix3D() {};

	Matrix3D(double[][] b) {
		for (int i = 0; i< 3; i++) {
			for (int j = 0; j<3; j++) {
				this.a[i][j] = b[i][j];
			}
		}
	};

	public void inverteLinha(int linhaA, int linhaB) {
		double temp;
		for (int i = 0; i < 3; i++) {
			temp = this.a[linhaA][i];
			this.a[linhaA][i] = this.a[linhaB][i];
			this.a[linhaB][i] = temp;
		}
	}

	public void setIdentity() {
		for (int i = 0; i < 3; i++) {
			for (int j = 0; j < 3; j++) {
				if(i == j) {
					this.a[i][j] = 1;
				}
				else {
					this.a[i][j] = 0;
				}
			}
		}
	}

	public Matrix3D matrixAdd(Matrix3D B) {
		Matrix3D C = new Matrix3D();
		for (int i = 0; i < 3; i++) {
			for (int j = 0; j < 3; j++) {
				C.a[i][j] = this.a[i][j] + B.a[i][j];
			}
		}
		return(C);
	}

	public Matrix3D matrixSub(Matrix3D B) {
		Matrix3D C = new Matrix3D();
		for (int i = 0; i < 3; i++) {
			for (int j = 0; j < 3; j++) {
				C.a[i][j] = this.a[i][j] - B.a[i][j];
			}
		}
		return(C);
	}

	public Matrix3D matrixMulti(Matrix3D B) {
		Matrix3D C = new Matrix3D();
		for (int i = 0; i < 3; i++) {
			for (int j = 0; j < 3; j++) {
				C.a[i][j] = this.a[i][0] * B.a[0][j] + this.a[i][1] * B.a[1][j] + this.a[i][2] * B.a[2][j]; 
			}
		}
		return(C);
	}

	public Vector3D vectorMulti(Vector3D B) {
		Vector3D C = new Vector3D();
		C.setX(this.a[0][0]*B.getX() + this.a[0][1]*B.getY() + this.a[0][2]*B.getZ());
		C.setY(this.a[1][0]*B.getX() + this.a[1][1]*B.getY() + this.a[1][2]*B.getZ());
		C.setZ(this.a[2][0]*B.getX() + this.a[2][1]*B.getY() + this.a[2][2]*B.getZ());
		return(C);
	}


	public Matrix3D scalarMult(double b) {
		Matrix3D C = new Matrix3D();
		for (int i = 0; i < 3; i++) {
			for (int j = 0; j < 3; j++) {
				C.a[i][j] = this.a[i][j] * b;
			}
		}
		return(C);
	}

	public Matrix3D scalarDiv(double b) {
		Matrix3D C = new Matrix3D();
		for (int i = 0; i < 3; i++) {
			for (int j = 0; j < 3; j++) {
				C.a[i][j] = this.a[i][j] / b;
			}
		}
		return(C);
	}

	public double getDeterminant() {
		double retorno = 0;
		for (int i = 0; i < 3; i++) {
			double elem = 1;
			int k = i;
			for (int j = 0; j < 3; j++) {
				elem = elem * this.a[j][k];
				k++;
				if (k == 3) {
					k = 0;
				}
			}
			retorno += elem;
		}

		for (int i = 2; i >= 0; i--) {
			double elem = 1;
			int k = i;
			for (int j = 0; j < 3; j++) {
				elem = elem * this.a[j][k];
				k--;
				if (k == -1) {
					k = 2;
				}
			}
			retorno -= elem;
		}

		return(retorno);
	}

	public Matrix3D getInverse() {
		Matrix3D B = new Matrix3D();
		B.setIdentity();

		Matrix3D C = new Matrix3D(this.a);


		for (int j = 0; j < 3; j++) {
			int i = j;
			for(int a = j;a<3;a++) {
				if (C.a[a][j] > C.a[i][j]) {
					i = a;
				}
			}

			C.inverteLinha(i,j);
			B.inverteLinha(i,j);


			double m = 1/C.a[j][j];

			for (int a = 0; a < 3; a++) {
				C.a[j][a] *= m;
				B.a[j][a] *= m;
			}

			for (int r = 0; r < 3; r++) {
				if (r != j) {
					m = -C.a[r][j];
					for (int a=0;a <3; a++) {
						C.a[r][a] += m*C.a[j][a]; 
						B.a[r][a] += m*B.a[j][a]; 
					}
				}
			}
		}

		return(B);
	}

	public void show() {
		for(int i = 0; i < 3; i++) {
			for(int j = 0; j < 3; j++) {
				System.out.print(this.a[i][j]);
				System.out.print("\t");

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

public class Vector3D {
	private double x,y,z;
	
	public void setX(double x) {
		this.x = x;
	}

	public void setY(double y) {
		this.y = y;
	}
	
	public void setZ(double z) {
		this.z = z;
	}
	
	public double getX() {
		return(x);
	}

	public double getY() {
		return(y);
	}
	
	public double getZ() {
		return(z);
	}
	
	Vector3D() {}
	
	Vector3D(double x, double y, double z) {
		this.x = x;
		this.y = y;
		this.z = z;
	}
	
	public Vector3D vectorAdd(Vector3D P) {
		Vector3D result = new Vector3D(x+P.getX(), y+P.getY(), z+P.getZ());
		return(result);
	}

	public Vector3D vectorSub(Vector3D P) {
		Vector3D result = new Vector3D(x-P.getX(), y-P.getY(), z-P.getZ());
		return(result);
	}
	
	public Vector3D scalarMult(double a) {
		Vector3D result = new Vector3D(x*a, y*a, z*a);
		return(result);
	}
	
	public Vector3D scalarDiv(double a) {
		Vector3D result = new Vector3D(x/a, y/a, z/a);
		return(result);
	}
	
	public double vectorDot(Vector3D P) {
		double result = x*P.getX() + y*P.getY() + z*P.getZ();
		return(result);
	}
	
	public Vector3D vectorCross(Vector3D Q) {
		Vector3D result = new Vector3D(x*Q.getZ()-z*Q.getY(), z*Q.getX()-x*Q.getZ(), x*Q.getY() - y*Q.getX());
		return(result);
	}
	
	public double vectorSize() {
		double result = Math.sqrt(x*x+y*y+z*z);
		return(result);
	}
	
	public void show() {
		System.out.print(this.x+"\t");
		System.out.print(this.y+"\t");
		System.out.println(this.z);
	}
	
}