Why do I keep getting a core dump

[Miles Hikari]

So my professor gave me a matrix class some time back and I decided to start messing around with it, to give it new functions for addition and multiplication, but I've hit an odd snag. I'm just getting started on the multiplication and I know that if you multiply a row vector by a column vector it's supposed to produce only a single value that can later be used as a scaler if you wanted. Since the return value for this particular function is a matrix I decided I wanter to try and get around that by making it by having that particular situation return a 1x1 matrix that would act as an int, and then I wanted to add the feature so that should my function receive a 1x1 matrix it treats it like a scaler. But for some reason. Thats the code I'm working on right now. But anytime I try and run it I get a message that read Segmentation Fault: Core Dumped, which if memory serves right means that the calculation would have ran for ever and to stop itself ended the program... At least thats what another prof told me. Anyway I'm really not sure what the issue is since the code it a copy paste of my working scaler multiplication function with a few light changes. Any help is appreciated.

Update: I added the code meant to multiply the row by the column and same core dump issue. I don't see any endless loops so... I'm quite confused.

Update: Since I was asked to clarify, all of the issues appear in matMul(mat a, mat b). All the other functions work perfectly fine, including matMul(mat a, int s)
Matrix class header

#include <random>
#include <iomanip>
#include <cmath>
#include <ctime>
class mat
{
public:
    mat(){A=NULL;}
    ~mat(){}


    mat(int r, int c){row=r; col=c;         ///Build an empty matrix of row r and column c
                    A=new double *[row];
                    for(int i=0; i<row; i++)
                    {
                        A[i]=new double[col];
                    }
                    for(int i=0; i<row; i++)
                    {
                        for(int j=0; j<col; j++)
                        {
                            A[i][j]=0.0;
                        }
                    }
            }


            int getrow(){return row;}
            int getcol(){return col;}     ///Retrieve the needed info
            //int getValue(int r, int c)
            //{
            //cout << A[r][c] << endl;
            //return A[r][c];
            //}


            void display()
            {
                for(int i=0; i<row; i++)
                {
                    for(int j=0; j<col; j++)
                    {
                        cout<<setw(8)<<A[i][j];
                    }
                    cout<<endl;
                }
                cout<<endl;
            }



        void ident(){  ///convert the current matrix into an indentity matrix
                    if(col==1){A[0][0]=1.0;}
                    else{
                    for(int i=0; i<row; i++)
                    A[i][i]=1.0;
                    }
                }

        void random_mat(double m)   ///Fill the matrix with random values
        {   double sum=0.0;
            double r;
            default_random_engine gen(time(NULL));
            uniform_real_distribution<double> rdist(-1*m, m);
            for(int i=0; i<row; i++)
            {
                for(int j=0; j<col; j++)
                {
                    r=rdist(gen);
                    A[i][j]=r;
                    sum = sum+abs(r);
                }
                A[i][i]=sum;
                sum=0.0;
            }
        }


mat matAdd(mat &a, mat &b) ///add two matrices to each other
    {
        int bRow = b.getrow();
    int bCol = b.getcol();
    mat c(bRow,bCol);
        for(int i=0; i<bRow; i++)
        {
            for(int j=0; j<bCol; j++)
            {
                c.A[i][j] = a.A[i][j]+b.A[i][j];
            }
            }
        return c;
    }

    mat matSub(mat &a, mat &b) ///subtract two matrices to each other
{
    int bRow = b.getrow();
    int bCol = b.getcol();
    mat c(bRow,bCol);
        for(int i=0; i<bRow; i++)
        {
            for(int j=0; j<bCol; j++)
            {
                c.A[i][j] = a.A[i][j]-b.A[i][j];
            }
            }
        return c;
}

mat matMul(mat a, int s) ///multiply a matrix and a scaler
{
    int aRow = a.getrow();
    int aCol = a.getcol();
    mat c(aRow,aCol);
        for(int i=0; i<aRow; i++)
        {
            for(int j=0; j<aCol; j++)
            {
                c.A[i][j] = a.A[i][j] * s;
            }
        }
        return c;
    }


mat matMul(mat a, mat b)
{

int aRow = a.getrow();
int aCol = a.getcol();
int bRow = b.getrow();
int bCol = b.getcol();

if (aRow == 1 && aCol == 1)             /// If matrix a has only one value treat it like a scaler to b
    {

           mat c(bRow,bCol);
        for(int i=0; i<bRow; i++)
        {
            for(int j=0; j<bCol; j++)
            {
                c.A[i][j] = b.A[i][j] * a.A[1][1];
            }
        }
        return c;
    }

    else if (bRow == 1 && bCol == 1)     ///if matrix b only has one value, treat it like a scaler to a
    {
           int tempA = a.getrow();
           int tempB = a.getcol();
           mat c(aRow,aCol);
        for(int i=0; i<aRow; i++)
        {
            for(int j=0; j<aCol; j++)
            {
                c.A[i][j] = a.A[i][j] * b.A[1][1];
            }
        }
        return c;
    }

    else if (aRow == 1 && bCol == 1 && aCol == bRow)///if a row is multiplied by a column, get a single number
        {
          mat c(1,1);
          int sum = 0;
        for(int i=0; i<aCol; i++)
        {

                sum = sum + a.A[1][i] * b.A[i][1];
        }
        c.A[1][1] = sum;
        return c;
        }

}






private:
    int row;
    int col;
    double ** A;
};

Test cpp

  #include <iostream>

using namespace std;
#include "matrix.h"





int main()
{   int r,c;
cout<<"enter rows and cols"<<endl;
//cin>>r>>c;
    mat A(1,3);
    A.random_mat(5);
    A.display();

    mat B(3,1);
    B.random_mat(3);
    B.display();

    mat C(1,1);
   C = C.matMul(A,B);
    C.display();
    return 0;
}

[Miles Hikari]

Yatora: What? I'm not using the site as a code dump? I'm asking a simple question and providing the code so someone can help me figure out why I keep getting a core dump

[jonnin]

most likely you have an array out of bounds.
figure out which functions work and which one crashes it.
then look deeper into that one, or provide more info here.

[Miles Hikari]

Sorry I guess I missed that part. All of the functions work except for matMul(mat a, mat b)

Every time I try to call upon that function is when I get the Segmentation Fault: Core Dump message. It also occurs no matter which of the if statements I try to use.

[Miles Hikari]

I figured it out, basic mistake. I was calling on location (1,1) in a matrix that only has a position (0,0)