2D Vector of Doubles sorting/editing issue - c++

Question

I am working on a 2D vector of doubles matrix solver and my matrices keep turning out incorrectly.
The intended matrix output at "Level 3" is {(top, left to right)3,4 over (bottom, left to right)1,2} but my code keeps outputting {2,1 over 3,4}. I keep trying to invert the values but whenever I do so I keep getting an out of bounds exception.
vector<double> gauss(mat B) {
int n = B.A.size();
for (int i=0; i<n-1; i++) {
// Search for maximum in this column
double maxEl = abs(B.getSlot(i,i));
int maxRow = i;
for (int k=i+1; k<n; k++) {
if (abs(B.getSlot(k,i)) > maxEl) {
maxEl = abs(B.getSlot(k,i));
maxRow = k;
}
}
// Swap maximum row with current row
for (int k=i; k<n+1;k++) {
double tmp = B.getSlot(k,maxRow);
B.editSlot(k,maxRow,B.getSlot(k,i));
B.editSlot(k,i,tmp);
}
cout << "\n\nlevel 3: \n";
B.display();
}
B.display();
// Solve equation Ax=b for an upper triangular matrix A
vector<double> x(n);
for (int i=n-1; i>=0; i--) {
x[i] = B.getSlot(i,n)/B.getSlot(i,i);
for (int k=i-1;k>=0; k--) {
B.editSlot(k,n,B.getSlot(k,n)-B.getSlot(k,i)*x[i]);
}
}
return x;
}
int main() {
int n = *Size of array is properly retrieved*
mat my_mat(n,n);
// Read input data
for (int i=0; i<n; i++) {
for (int j=0; j<n; j++) {
double myDub;
inFile >> myDub;
my_mat.editSlot(i,j,myDub);
}
}
// Calculate solution
vector<double> x(n);
x = gauss(my_mat);
}
And my class code is as follows
class mat
{
public:
mat(int x,int y){
int row = x;
int col = y;
n=row;
A = vector<vector<double>>(row,vector<double>(row,0));
for(int i=0; i<row; i++)
{
for(int j=0; j<col; j++)
{
cout<<setw(6)<<A[i][j];
}
cout<<endl;
}
}
void editSlot(int x, int y, double val){A[y][x] = val;}
double getSlot(int x, int y){return A[y][x];}
void display()
{
for(int i=0; i<n; i++)
{
for(int j=0; j<n; j++)
{
cout<<setw(6)<<A[j][i];
}
cout<<endl;
}
cout<<endl;
}
vector<vector<double>> A;
private:
int n;
};

Answer 1

Try to change your input loop:
// Read input data
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
double myDub;
inFile >> myDub;
my_mat.editSlot(j, i, myDub); // < - j, i swapped.
}
}
Can you provide sample input that you use and what output you expect?