#include "TrueBASIC.h"
void draw_axes(float xmin, float xmax, float ymin, float ymax);

void draw_axes(float xmin, float xmax, float ymin, float ymax)
{
    float dx, dy, tx, ty, x, x0, y, y0;
    int itick, ntick;

    // number of tick marks
    ntick = 10;
    // dx distance between tick marks on x axis
    dx = (xmax - xmin)/ntick;
    // dy distance between tick marks on y axis
    dy = (ymax - ymin)/ntick;
    // include margin in window statement
    GWindow(xmin - dx, ymin - dy, xmax + dx, 
            ymax + dy);
    x0 = max(0, xmin);
    if(ymin*ymax < 0)
        y0 = 0;
    else
        y0 = ymin;
    GWline(xmin, y0, xmax, y0);             // horizontal axis
    GWline(x0, ymin, x0, ymax);             // vertical axis
    tx = 0.1*dy;                            // size of tick mark
    ty = 0.1*dx;
    for(itick = 0; itick <= ntick; ++itick)
    {
        x = xmin + itick*dx;
        GWline(x, y0 - tx, x, y0 + tx);
                                            // draw ticks on x axis
        y = ymin + itick*dy;
        GWline(x0 - ty, y, x0 + ty, y);
                                            // draw ticks on y axis
    }
}