The following code works but needs Java - File I/O . The current output is:
Question:
The following code works but needs Java - File I/O .
The current output is:
16 17
26 22
I want the user to input the values instead of the current hard-coded inputs which are highlighted in the java code below.
Format: This first line should contain the order of the matrix, then the first matrix, in row-major order, then the second matrix by a blank line, then the order of the next matrix pair...
Thus, for the given input.
Given input:
2
2 1 6 7
1 5 4 3
The output will be:
16 17
26 22
import java.lang.*;
public class GFG {
// Method 1
// Function to multiply matrices
public int[][] multiply(int[][] A, int[][] B)
{
// Order of matrix
int n = A.length;
// Creating a 2D square matrix with size n
// n is input from the user
int[][] R = new int[n][n];
// Base case
// If there is only single element
if (n == 1)
// Returning the simple multiplication of
// two elements in matrices
R[0][0] = A[0][0] * B[0][0];
// Matrix
else {
// Step 1: Dividing Matrix into parts
// by storing sub-parts to variables
int[][] A11 = new int[n / 2][n / 2];
int[][] A12 = new int[n / 2][n / 2];
int[][] A21 = new int[n / 2][n / 2];
int[][] A22 = new int[n / 2][n / 2];
int[][] B11 = new int[n / 2][n / 2];
int[][] B12 = new int[n / 2][n / 2];
int[][] B21 = new int[n / 2][n / 2];
int[][] B22 = new int[n / 2][n / 2];
// Step 2: Dividing matrix A into 4 halves
split(A, A11, 0, 0);
split(A, A12, 0, n / 2);
split(A, A21, n / 2, 0);
split(A, A22, n / 2, n / 2);
// Step 2: Dividing matrix B into 4 halves
split(B, B11, 0, 0);
split(B, B12, 0, n / 2);
split(B, B21, n / 2, 0);
split(B, B22, n / 2, n / 2);
// Using Formulas as described in algorithm
// M1:=(A1+A3)×(B1+B2)
int[][] M1
= multiply(add(A11, A22), add(B11, B22));
// M2:=(A2+A4)×(B3+B4)
int[][] M2 = multiply(add(A21, A22), B11);
// M3:=(A1−A4)×(B1+A4)
int[][] M3 = multiply(A11, sub(B12, B22));
// M4:=A1×(B2−B4)
int[][] M4 = multiply(A22, sub(B21, B11));
// M5:=(A3+A4)×(B1)
int[][] M5 = multiply(add(A11, A12), B22);
// M6:=(A1+A2)×(B4)
int[][] M6
= multiply(sub(A21, A11), add(B11, B12));
// M7:=A4×(B3−B1)
int[][] M7
= multiply(sub(A12, A22), add(B21, B22));
// P:=M2+M3−M6−M7
int[][] C11 = add(sub(add(M1, M4), M5), M7);
// Q:=M4+M6
int[][] C12 = add(M3, M5);
// R:=M5+M7
int[][] C21 = add(M2, M4);
// S:=M1−M3−M4−M5
int[][] C22 = add(sub(add(M1, M3), M2), M6);
// Step 3: Join 4 halves into one result matrix
join(C11, R, 0, 0);
join(C12, R, 0, n / 2);
join(C21, R, n / 2, 0);
join(C22, R, n / 2, n / 2);
}
// Step 4: Return result
return R;
}
// Method 2
// Function to subtract two matrices
public int[][] sub(int[][] A, int[][] B)
{
//
int n = A.length;
//
int[][] C = new int[n][n];
// Iterating over elements of 2D matrix
// using nested for loops
// Outer loop for rows
for (int i = 0; i < n; i++)
// Inner loop for columns
for (int j = 0; j < n; j++)
// Subtracting corresponding elements
// from matrices
C[i][j] = A[i][j] - B[i][j];
// Returning the resultant matrix
return C;
}
// Method 3
// Function to add two matrices
public int[][] add(int[][] A, int[][] B)
{
//
int n = A.length;
// Creating a 2D square matrix
int[][] C = new int[n][n];
// Iterating over elements of 2D matrix
// using nested for loops
// Outer loop for rows
for (int i = 0; i < n; i++)
// Inner loop for columns
for (int j = 0; j < n; j++)
// Adding corresponding elements
// of matrices
C[i][j] = A[i][j] + B[i][j];
// Returning the resultant matrix
return C;
}
// Method 4
// Function to split parent matrix
// into child matrices
public void split(int[][] P, int[][] C, int iB, int jB)
{
// Iterating over elements of 2D matrix
// using nested for loops
// Outer loop for rows
for (int i1 = 0, i2 = iB; i1 < C.length; i1++, i2++)
// Inner loop for columns
for (int j1 = 0, j2 = jB; j1 < C.length;
j1++, j2++)
C[i1][j1] = P[i2][j2];
}
// Method 5
// Function to join child matrices
// into (to) parent matrix
public void join(int[][] C, int[][] P, int iB, int jB)
{
// Iterating over elements of 2D matrix
// using nested for loops
// Outer loop for rows
for (int i1 = 0, i2 = iB; i1 < C.length; i1++, i2++)
// Inner loop for columns
for (int j1 = 0, j2 = jB; j1 < C.length;
j1++, j2++)
P[i2][j2] = C[i1][j1];
}
// Method 5
// Main driver method
public static void main(String[] args)
{
long startTime = System.nanoTime();
long start = System.currentTimeMillis();
// Display message
System.out.println(
"Strassen Multiplication Algorithm Implementation For Matrix Multiplication :\n");
// Create an object of Strassen class
// in he main function
GFG s = new GFG();
// Size of matrix
// Considering size as 4 in order to illustrate
int N = 2;
// Matrix A
// Custom input to matrix
int[][] A = { { 2, 1 },
{ 1, 5 }};
// Matrix B
// Custom input to matrix
int[][] B= { { 6, 7},
{ 4, 3 }};
// Matrix C computations
// Matrix C calling method to get Result
int[][] C = s.multiply(A, B);
// Display message
System.out.println(
"\nProduct of matrices A and B : ");
// Iterating over elements of 2D matrix
// using nested for loops
// Outer loop for rows
for (int i = 0; i < N; i++) {
// Inner loop for columns
for (int j = 0; j < N; j++)
// Printing elements of resultant matrix
// with whitespaces in between
System.out.print(C[i][j] + " ");
// New line once the all elements
// are printed for specific row
System.out.println();
long endTime = System.nanoTime();
long totalTime = (endTime - startTime)/1000000;
// System.out.println(totalTime);
}
}
}
Income Tax Fundamentals 2013
ISBN: 9781285586618
31st Edition
Authors: Gerald E. Whittenburg, Martha Altus Buller, Steven L Gill