Answer:
<u><em>Code:</em></u>
#include <iostream>
#include <fstream>
#include <cctype>
#include <cmath>
#include <vector>
#include <float.h>
using namespace std;
typedef vector<vector<double> > C2DArray;
void Matrix_Mult(bool* error_flag, const int mRows, const int nCols, const int pCols, const C2DArray A_Matrix, const C2DArray B_Matrix, C2DArray& C_Matrix) {
int i = A_Matrix.size(), j = A_Matrix[0].size(), k = B_Matrix[0].size();
double dummy;
if ((j != B_Matrix.size()) || (i != mRows) || (j != nCols) || (k != pCols)) *error_flag = true;
if ((C_Matrix.size() != i) || (k != C_Matrix[0].size())) *error_flag = true;
if (!(*error_flag)){
for (k = 0; k < mRows; k++) { // Do each row of A with each column of B
for (i = 0; i < pCols; i++) {
dummy = 0.0;
for (j = 0; j < nCols; j++) {
dummy += A_Matrix[k][j]*B_Matrix[j][i];
} // End for j
C_Matrix[k][i] = dummy;
} // End for i
} // End for k
}
return;
} // End Matrix_Mult
int main()
{char rflag = 0; //Readiness flag
cout << " Mat_Mul1 (7 June 2013)\n";
cout << "=========================================================================== \n";
cout << "This program multiplies two matrices, [A] and [B]: [A][B] = [C].\n";
cout << "[A] is M X N, [B] is N X P, and [C] is M X P\n";
cout << "The dimensions of the [A] and [B] matrices, M, N, and P, should \n";
cout << "have been saved beforehand in a file named mulmatdat.\n";
cout << "mulmatdat should be in the same folder as the Mat_Mul1 executable.\n";
cout << "The next values of mulmatdat should be the entries for matrix [A],\n";
cout << "with data for row 1 first, then row 2, then row 3, etc.\n";
cout << "The entries for the [B] matrix should follow, in the same order.\n";
cout << "\nThe data is assumed to be of type double. Variables used within this program\n";
cout << "are type double.\n";
cout << "\nThe output is written to the file mulmatout.txt.\n";
cout << "\nIs everything ready (are you ready to continue?)? If yes, Enter y. \n";
cout << "Otherwise Enter any other key. \n";
cin >> rflag;
if (toupper(rflag) == 'Y') {
C2DArray A, B, C; // A, B, and C Matrices
int i, j, mDim, nDim, pDim; // Array index variables and matrix dimensions
bool erFlag = false; // Error flag
ifstream in("mulmatdat.txt", ios::in);
if (!in) {
cout << "\nCannot open the input file.\n";
cout << "\nEnter any key to continue. \n";
cin >> rflag;
return 0;
}
in >> mDim >> nDim >> pDim; //Input the Matrices' dimensions from the file
if ((mDim < 1) || (nDim < 1) || (pDim < 1)){
cout << "\nInvalid dimension entered. Program terminated. \n";
cout << "\nEnter any key to continue. \n";
cin >> rflag;
in.close(); //Close the input file before terminating
return 0;
}
ofstream out("mulmatout.txt", ios::out);
if (!out) {
cout << "\nCannot open the output file. Program terminated.\n";
cout << "\nEnter any key to continue. \n";
cin >> rflag;
in.close(); //Close the input file before terminating
return 0;
}
// Beginning of try block, if vector re-sizing unsuccessful
try {
// Resize the arrays to the appropriate sizes
A.resize(mDim); // M rows
B.resize(nDim); // N rows
C.resize(mDim); // M rows
for (i = 0; i < mDim; i++){
A[i].resize(nDim); // M columns
C[i].resize(pDim); // P columns
} // End for i
for (i = 0; i < nDim; i++){
B[i].resize(pDim); // P columns
} // End for i
} // End of try block
catch (bad_alloc& xa) { // Catch block, for exceptions
in.close();
out.close();
cerr << "\nIn catch block, so an exception occurred: " << xa.what() << "\n";
cout << "\nEnter any key to continue. \n";
cin >> rflag;
return 0;
} // End of catch block
for (i = 0; i < mDim; i++){ //Input the A Matrix from the file
for (j = 0; j < nDim; j++){
in >> A[i][j];
}//End for j
}//End for i
for (i = 0; i < nDim; i++){ //Input the B Matrix from the file
for (j = 0; j < pDim; j++){
in >> B[i][j];
}//End for j
}//End for i
in.close(); //Close the input file
Matrix_Mult(&erFlag, mDim, nDim, pDim, A, B, C);
if (erFlag){
cout << "Inconsistent data sent to Matrix_Mult routine. Matrix multiplication NOT performed. Check data before running again.\n";
}
else {
out.precision(DBL_DIG);
out << "\nThe A matrix follows:\n";
out << "\n";
for (i = 0; i < mDim; i++){
for (j = 0; j < nDim; j++){
out << A[i][j] << " ";
} // End for j
out << "\n";
}//End for i
out << "\nThe B matrix follows:\n";
out << "\n";
for (i = 0; i < nDim; i++){
for (j = 0; j < pDim; j++){
out << B[i][j] << " ";
} // End for j
out << "\n";
}//End for i
out << "\nThe product matrix, C, follows:\n";
out << "\n";
for (i = 0; i < mDim; i++){
for (j = 0; j < pDim; j++){
out << C[i][j] << " ";
} // End for j
out << "\n";
}//End for i
cout << "\nDone! The solution is in the text file mulmatout.txt \n";
} // End else !erFlag
out.close();
}
else cout << "\nNot ready. Try again when ready with information. \n";
cout << "\nEnter any key to continue. \n";
cin >> rflag;
return 0;
}
<u><em></em></u>