Why is my grapher printing multiple instances of the function? C++

Question

I have this program that graphs simple parametric equations on a board of a defined length and width by me. It compiles fine but prints multiple instances of the function in different positions of the graph. If someone could please help me figure out why I am getting this output, I would greatly appreciate it. I included comments throughout the code to help understand what is going on. I do not have enough reputation to post a picture of the output but if you compile and execute it you will see what I am talking about.

#include <iostream>
#include <cstdlib>
#include <unistd.h>
#include <time.h>
#include <cmath>
using namespace std;

#define N 25
#define M 60

/*
  This function prints the board each time it is called and places an *
  in the place corresponding to the value of the function.
*/
void print_board(char p[M][N]) {
    int i, j;
    for (i=0; i<=N; i++) {
        for (j=0; j<=M; j++)
                 if (i==0)      cout << '=';
            else if (j==0)      cout << '|';
            else if (i==N)      cout << '=';
            else if (j==M)      cout << '|';
            else if (p[i][j]== '*') cout << '*';
            else            cout << ' ';
        cout << endl;
    }
}
/*
  These functions accepts an integer for time and computes a value for x and y
  for the parametirc equations given and returns each.
*/
int fx(int t) {

    int x = t;

    return x;
}

int fy(int t) {

    //int y = 5 * sin(0.2 * t) + 15;
    int y = (pow(t,2)/60) - t + 25;

    return y;
}

/*
  This function copies the old board and comoputes what the new board is.
*/
void next_board(char p[M][N], int t) {
    int i, j;

    //copies the old board
    int q[M][N];
    for (i=0; i<=N; i++) {
        for (j=0; j<=M; j++) {
            q[i][j] = p[i][j];
        }
    }

    //creates the new board
    int x, y;
    for (i=0; i<=N; i++) {
        for (j=0; j<=M; j++) {
            x = fx(t);
            y = fy(t);

            if (i == y && j == x) {
                p[i][j] = '*';  //stores an * for the values of x and y
            }
        }
    }

}

int main() {

    char p[M][N];

    print_board(p);

    int t = 0;
    while(t <= M) {
        cout << string(80, '\n');

        next_board(p , t);
        print_board(p);
        usleep(20000);

        t++;
    }

    return 0;
}

Please help and thank you for all who try!

Answer 1

everywhere in your program where you have

char p[M][N]

change them to

char p[N][M]

and you should get the results that youd expect, your mixing axes in your program

heres the whole working code if youd like

#include <iostream>
#include <cstdlib>
#include <unistd.h>
#include <time.h>
#include <cmath>
#include <string>
using namespace std;

#define N 25
#define M 60

/*
This function prints the board each time it is called and places an *
in the place corresponding to the value of the function.
*/
void print_board(char p[N][M]) {
    int i, j;
    for (i = 0; i <= N; i++) {
        for (j = 0; j <= M; j++)
            if (i == 0)      cout << '=';
            else if (j == 0)      cout << '|';
            else if (i == N)      cout << '=';
            else if (j == M)      cout << '|';
            else if (p[i][j] == '*') cout << '*';
            else            cout << ' ';
            cout << endl;
    }
}
/*
These functions accepts an integer for time and computes a value for x and y
for the parametirc equations given and returns each.
*/
int fx(int t) {

    int x = t;

    return x;
}

int fy(int t) {

    //int y = 5 * sin(0.2 * t) + 15;
    int y = (pow(t, 2) / 60) - t + 25;

    return y;
}

/*
This function copies the old board and comoputes what the new board is.
*/
void next_board(char p[N][M], int t) {
    int i, j;

    //copies the old board
    int q[M][N];
    for (i = 0; i <= N; i++) {
        for (j = 0; j <= M; j++) {
            q[i][j] = p[i][j];
        }
    }

    //creates the new board
    int x, y;

    for (i = 0; i <= N; i++) {

        for (j = 0; j <= M; j++) {
            x = fx(t);
            y = fy(t);

            if (i == y && j == x) {
                p[i][j] = '*';  //stores an * for the values of x and y
            }
        }
    }

}

int main() {

    char p[N][M];

    print_board(p);

    int t = 0;
    while (t <= M) {
        cout << string(80, '\n');

        next_board(p, t);
        print_board(p);
        usleep(20000);

        t++;
    }

    return 0;
}