用C实现exp函数

#include "stdio.h"

#include "stdlib.h"

#include "math.h"

#include "graphics.h"

#define fnx(x) (x0+x*s1)

#define fny(y) (y0-y*s1)

#define f(x) 0.2*(x)*(x)

void setup(void);

int x0,y0,maxx,maxy;

float s1;

main()

{

int xs,ys;

float x,y,x1,y1,x2,y2,dx,i;

setup();

x1=0;x2=5;dx=0.00001;

clearviewport();

setcolor(14);

xs=fnx(x1);ys=fny(0);

xs=fnx(x2);

xs=fnx(0);ys=0;

ys=fny(0);

x=x1;y=f(x);xs=fnx(x);ys=fny(y);

for(i=x1;i<x2;i+=dx)

{ putpixel(xs,ys,4);

x+=dx;y=f(x);xs=fnx(x);ys=fny(y);}

getch();

restorecrtmode();

}

void setup(void)

{

int driver,mode;

driver=DETECT;

initgraph(&driver,&mode,"");

maxx=getmaxx();

maxy=getmaxy();

x0=150;y0=150;s1=10;

setviewport(0,0,maxx,maxy,1);

}