For Adas: Parallel Numerical Sequence in Matrix V.2

#include<iostream>
using namespace std;

int i, j, arraySize;

void fillArray(double **);
void showArray(double **);
void showInvDiag(double **);
void showOtherDiags(double **);

/* Trouble arises when calling 'showInvDiag'
void displayEverything(double **array){
    showArray(array);
    showInvDiag(array);
    showOtherDiags(array);
}
*/

int main(){
    cout << "Number of lines and columns: "; cin >> arraySize;
    // Create the 2D array
    //****************************************************************
    double **array;
    array = new double *[arraySize];
    for(i = 0; i < arraySize; i++) array[i] = new double [arraySize];
    //****************************************************************

    fillArray(array);
    //displayEverything(array); // Not working fully
    showArray(array);
    showInvDiag(array);
    showOtherDiags(array);

    return 0;
}

void fillArray(double **array){
    for(i = 0; i < arraySize; i++){
        for(j = 0; j < arraySize; j++){
            cout << "(" << i << ", "<< j << ") = ";
            cin >> array[i][j];
        }
    }
    cout << endl;
}
void showArray(double **array){
    for(i = 0; i < arraySize; i++){
        for(j = 0; j < arraySize; j++) cout << array[i][j] << " ";
        cout << endl;
    }
    cout << endl;
}
void showInvDiag(double **array){
    double *diagSum;
    *diagSum = 0;
    j = arraySize - 1;

    cout <<"\nInverse Diagonal values are: " << endl;

    for(i = 0; i < arraySize; i++){
        *diagSum += array[i][j];
        cout << array[i][j--] << " ";
    }

    cout << "\n\nInverse diagonal arithmetic average: " << *diagSum / arraySize << endl;

    delete diagSum;
}
void showOtherDiags(double **array){
    int holdX = 0, holdY = 0;
    int x, y;
    j = 1;

    cout << "\nOther inverse diagonals." << endl;
    cout << "*************************************" << endl;
    // Upper-Left Diagonal Triangle
    while(j <= arraySize - 1){
        x = holdX; y = holdY;

        for(i = 0; i < j; i++) cout << array[x++][y--] << " ";
        cout << endl;

        holdY++; j++;
    }

    // Lower-Right Diagonal Triangle
    j = arraySize - 1, holdX = 1, holdY = arraySize - 1;

    while(j >= 1){
        x = holdX; y = holdY;

        for(i = 0; i < j; i++) cout << array[x++][y--] << " ";
        cout << endl;

        holdX++; j--;
    }
    cout << "*************************************" << endl;
}