Matrix and vector multiplication

[audrius69]

Hello, so I have an assigment in uni to write program that multiplies matrix by the vector. Also it must be able to add vector or matrixes together. vector.h and vector.cpp was provided as an example and they seem to work. I tried wiriting matrix.h and matrix.cpp according to the example. Any comments would be appreciated. Thanks

//-------------------------------------------------------------------
/*vector.h*/
/*==========================*/
#ifndef VECTOR_H_INCLUDED
#define VECTOR_H_INCLUDED

#include <cstddef>
#include <stdio.h>
#include <cstdlib>

class Matrix;
class Vector
{
public:
   Vector(){n=0;x=0;}
   Vector(int n){allocation(n);}
   Vector(char* file);
   Vector(Vector& A);

   ~Vector();

   void allocation(int ln);
    void out(char* s);
    void naujas(int ln);
    void operator =(const Vector& A);
    double& operator [](int i);

    friend Vector operator+(const Vector& A, const Vector& B);
private:
    int n; 
    double *x;
};
#endif // VECTOR_H_INCLUDED

/*matrix.h*/
/*===========================*/
#ifndef MATRIX_H_INCLUDED
#define MATRIX_H_INCLUDED

#include <cstddef>
#include <stdio.h>
#include <cstdlib>

class Matrix
{
public:
   Matrix(){n=0;m=0;y=0;}
   Matrix(int n){allocation(n,m);}
   Matrix(char* file);
   Matrix(Matrix& A);

   ~Matrix();

   void allocation(int ln, int lm);
    void print(char* s);
    void naujas(int ln);  
private:
    int n; //Matrix rows
    int m; // Matrix columns
    double *y;
};
#endif // MATRIX_H_INCLUDED

/*vector.cpp*/
/*=========================*/
#include "vector.h"
#include <assert.h>
#include <cstdlib>

void Vector::allocation(int ln)
{
    n=ln;
    x=new double[n];
    assert(x!=0);
}

Vector::Vector(char* file)
{
    FILE* in;
    int n;
    double dl;

    in = fopen(file, "rt");
    assert(in != 0);

    fscanf(in,"%d\n", &n);
    allocation(n);

    for(int i=0;i<n;i++){
        fscanf(in, "%lf", &dl);
        x[i]=dl;
    }
    fclose(in);
}

Vector::~Vector()
{
    if(x!=0)
        delete []x;
}

void Vector::out(char* s)
{
    printf("%s:\n",s);
    if(x==0){
        printf("Empty\n\n");
        return;
    }
    for(int i=0;i<n;i++){printf("%8.4f",x[i]);}
    printf("\n\n");
}

Vector operator +(const Vector& A, const Vector& B)
{
    if(A.n != B.n){
        printf("Klaida vektoriaus klaseje: blogas indeksas\n");
        exit(1);
    }
    Vector Temp(A.n);
    for(int i=0;i<A.n;i++){Temp.x[i]=A.x[i]+B.x[i];
    }
    return Temp;
}

void Vector::operator =(const Vector& A)
{
    if(n!=A.n) {naujas(A.n);}
    for(int i=0;i<n;i++) {x[i]=A.x[i];}
}

void Vector::naujas(int ln)
{
    if(n==ln){return;}
    if(x!=0){delete []x;}
    allocation(n);
}

Vector::Vector(Vector& A)
{
    allocation(A.n);
    for(int i=0;i<n;i++) {x[i]=A.x[i];}
}

double& Vector::operator [](int i)
{
    if(i<0 || i>=n){
        printf("Klaida\n");
        exit(1);
    }
    return x[i];
}

/*matrix.cpp*/
/*============================*/
#include "matrix.h"
#include <assert.h>
#include <cstdlib>
#include <iostream>
using namespace std;


void Matrix::allocation(int ln, int lm)
{
    n=ln;
    m=lm;

    double *y= (double *)malloc(n*m*sizeof(double));

    assert(y!=0);
}

Matrix::Matrix(char* file)
{
    FILE* in;
    int n,m;
    double dl;

    in = fopen(file, "rt");
    assert(in != 0);

    fscanf(in,"%d", &n);
    fscanf(in,"%d", &m);
    allocation(n,m);

    for(int i=0;i<n; i++){
            printf("\n");
    for(int j=0; j<m; j++){
        fscanf(in, "%lf", &dl);
        *(y+i*m+j)=dl;

    }
}
    fclose(in);
}

Matrix::~Matrix()
{
       for (int i=0;i<n;i++){
        delete []y;}
}

void Matrix::print(char* s)
{
    printf("%s:\n",s);
    if(y==0){
        printf("Empty\n\n");
        return;
    }
    for(int i=0;i<n;i++){ printf("\n");
            for (int j=0;j<m;j++){printf("%lf ", *(y+i*m+j));}}
    printf("\n\n");
}

/*double& Matrix::operator [][](int i, int j)

/*main.cpp*/
/*======================*/
#include <iostream>
#include "vector.h"
#include "matrix.h"

using namespace std;

int main()
{
    Matrix M("m_a.dat");

    // commented this part out, beause without it program works
    /*Matrix N("m_b.dat");
    M.print("M");
    N.print("N");

    Vector A("v_a.dat");
    Vector B("v_b.dat");
    Vector C("v_c.dat");
    Vector D(3);

    A.out("A");
    B.out("B");
    C.out("C");

    D = A+B+C;
    D.out("D=A+B+C");*/
    return 0;
}

[salem c]

> double *y= (double *)malloc(n*m*sizeof(double));
..
> delete []y;
This is wrong.
You can't mix and match your allocators.
malloc pairs with free
new pairs with delete
new[] pairs with delete[]

> #include <cstddef>
> #include <stdio.h>
> #include <cstdlib>
Now try replacing all your printf / scanf etc with corresponding C++ methods.

[audrius69]

Hi, sorry it took me so long. I replaced scanf and printf as you said. Also changed matrix declaration to new, but my program still doesnt work. I think the problem might be in matrix allocation or something to do with pointers (I still dont understand them well) This is matrix.h and matrix.cpp now. I am really lost and dont know what to do here. Thanks.

/*matrix.h*/
/*====================*/
#ifndef MATRIX_H_INCLUDED
#define MATRIX_H_INCLUDED

#include <cstddef>
#include <stdio.h>
#include <cstdlib>

class Matrix
{
public:
   Matrix(){n=0;m=0;matrix=0;}
   Matrix(int n){allocation(n,m);}
   Matrix(char* file);
   Matrix(Matrix& A);

   ~Matrix();

   void allocation(int ln, int lm);
    void print(char* s);
private:
    int n; //Matrix rows
    int m; // Matrix columns
    double **matrix;
};

#endif // MATRIX_H_INCLUDED

/*matrix.cpp*/
/*====================*/
#include "matrix.h"
#include <assert.h>
#include <cstdlib>
#include <stdio.h>
#include <cstddef>
#include <iostream>
#include <fstream>

using namespace std;

void Matrix::allocation(int ln, int lm)
{
    n=ln;
    m=lm;

    *matrix= new double [n*m];
    for (int i=1;i<n;i++){
            matrix[i]=matrix[0]+i*m;
    }
    assert(matrix!=0);
}

Matrix::Matrix(char* file)
{
    ifstream inFile;
    inFile.open(file);
    inFile >> n;
    inFile >> m;
    allocation(n,m);

    for(int i=0;i<n; i++){
    for(int j=0; j<m; j++){

        inFile >> matrix[n][m];
    }
}

   inFile.close();
}

Matrix::~Matrix()
{
      if (n) delete [] matrix[0];
        delete [] matrix;
}

void Matrix::print(char* s)
{
    cout << s;
    if(matrix==0){
        cout << "Empty" << endl;
        return;
    }
    for(int i=0;i<n;i++){ cout << endl;;
            for (int j=0;j<m;j++){cout << matrix[n][m];}}
    cout << endl;
}

[salem c]

> *matrix= new double [n*m];
You need to new yourself a matrix, before dereferencing it.

[audrius69]

Thanks, got it working like this:

void Matrix::allocation(int ln, int lm)
{
    n=ln;
    m=lm;

    matrix= new double*[n];
        for (int i=0;i<n;i++){
    matrix[i]= new double[m];
    }
}

Matrix::Matrix(char* file)
{
    double temp;
    ifstream inFile;
    inFile.open(file);
    inFile >> n;
    inFile >> m;
    allocation(n,m);

    for(int i=0;i<n; i++){
    for(int j=0; j<m; j++){
        inFile >> temp;
        matrix[i][j]=temp;
    }
}
   inFile.close();
}

Matrix::~Matrix()
{
      for(int i=0;i<n;i++){
            delete [] matrix[i];}
        delete [] matrix;
}