Graphing calc

/*
This program creates a basic graph using whole numbers. maxX sets the largest x value and has y adjust according to it. The function may be changed in the formula function. Possible improvments include allowing user to change function from input, allowing decimal numbers, and negative quadrants.
*/

#include <iostream>
#include <cmath>
#include <string>
#include <iomanip>
using namespace std;

int digit(int number) {
    //This function gathers digits to set width of y numb line
    int count = 0;
    while(number != 0) {
        number = number / 10;
        count++;
    }
    return count;
}

int formula(int x){
    //this function serves to update maxY and f(x) using only one value
    return pow(x,2);

}

int main() {
    int maxX= 5;
    int maxY=formula(maxX);
    for(int y=0; y<=maxY; y++){
        cout << setw(digit(maxY)) << maxY-y;
        for(int x=0; x<=maxX; x++){
            if(formula(x)==(maxY-y)){
                cout << "o";
            }
            else
                cout << " ";
        }
        cout << endl;
    }
    return 0;
}