Midpoint Algorithm, Bresenham, Drawing a parabola

So I’ve been trying to make a source code using OpenGL that plots a parabola (y=(1/100)*x^2) with the range of x being (-50<=x<=50). However, whenever I try running the dumb script, I’d only get a blank window. Could anyone show me where I goofed up? I’m trying to plot this using the Bresenham (Midpoint) Algorithm (My professor won’t allow any other methods than the Midpoint method)

#include <gl\glut.h>
#include <stdlib.h>
#include <math.h>
#include <stdio.h>

void init(void)
{
    glutInitWindowPosition(100,100);
    glutInitWindowSize(640,480);
    glutCreateWindow("Parabola: Midpoint Algorithm");
    glClearColor(1.0,1.0,1.0,0.0);
    glColor3f(0.0,0.0,0.0);
    gluOrtho2D(-100.0,100.0,100.0,100.0);
    glPointSize(10);
}
void setPixel(GLint xCoord, GLint yCoord)
{
    glBegin(GL_POINTS);
    glVertex2i(xCoord, yCoord);
    glEnd();
}

void bres_para(int x0, int y0, int xEnd, int yEnd)
{
    int k;
    float p, xIncrement, yIncrement, x=x0,y=y0, xx, yy;

    //x가 50이하일 경우를 먼저 작성한다
    for (k=0;k<=50;k++)
    {
        xIncrement=1.0;
        x+=xIncrement;
        yIncrement=(2*x+1)/100;
        y+=yIncrement;
        p=((x+1)*(x+1))-100*(y+0.5);
        xx=x+1;
        yy=y+1;
        if (p<=0)
        {
            p=p+2*x+1;
            setPixel(xx,round(y));
            setPixel(-(xx),round(y));
        }
        else
        {
            p=p+2*x-99;
            setPixel(xx,round(yy));
            setPixel(-(xx),round(yy));
        }
        printf("%f,%f
",x,y);
    }

    //x가 50보다 클 경우를 다음으로 작성한다
}

void draw(void)
{
    glClear(GL_COLOR_BUFFER_BIT);
    bres_para(0,0,50,25);
    glFlush();
}

int main(int argc, char**argv)
{
    glutInit(&argc,argv);
    init();
    glutDisplayFunc(draw);
    glutMainLoop();
}

You’re missing a negative sign for the bottom parameter.