Fractal Fern Paul Bourke Jay Link

```   /*--------------------------------------------------*
Pre-SVGAlib code by Paul Bourke:
Usage:  <program name> <n steps>
(Try 50,000 steps -- it won't take long).
*--------------------------------------------------*/

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <vga.h>

#define NX 1024
#define NY 768
#define MIN(x,y) (x < y ? x : y)

double a[4] = {0.0,0.2,-0.15,0.75};
double b[4] = {0.0,-0.26,0.28,0.04};
double c[4] = {0.0,0.23,0.26,-0.04};
double d[4] = {0.16,0.22,0.24,0.85};
double e[4] = {0.0,0.0,0.0,0.0};
double f[4] = {0.0,1.6,0.44,1.6};

int main(int argc, char *argv[])
{
int i,j,k;
int n;
int ix,iy;
double r,x,y,xlast=1,ylast=1;
double xmin=1e32,xmax=-1e32,ymin=1e32,ymax=-1e32,scale,xmid,ymid;

if (argc < 2) {
fprintf(stderr,"Usage: %s nsteps\n",argv[0]);
exit(0);
}
n = atoi(argv[1]);

vga_init();
vga_setmode(G1024x768x256);
vga_setcolor(15);

for (j=0; j < 2 ; j++) {
for (i=0; i < n; i++) {
r = rand() % 100;
if (r < 10)
k = 0;
else if (r < 18)
k = 1;
else if (r < 26)
k = 2;
else
k = 3;
x = a[k] * xlast + b[k] * ylast + e[k];
y = c[k] * xlast + d[k] * ylast + f[k];
xlast = x;
ylast = y;
if (x < xmin) xmin = x;
if (y < ymin) ymin = y;
if (x > xmax) xmax = x;
if (y > ymax) ymax = y;
if (j == 1) {
scale = MIN(NX / (xmax - xmin),NY / (ymax - ymin));
xmid = (xmin + xmax) / 2;
ymid = (ymin + ymax) / 2;
ix = NX / 2 + (x - xmid) * scale;
iy = NY / 2 + (y - ymid) * scale;
vga_drawpixel(ix, iy);
}
}
}

vga_getch();
vga_setmode(TEXT);
return 0;
}
```