cov.cpp

卷积的计算

#include"stdio.h"
#include "math.h"
#include "graphics.h"
#include "stdlib.h"
#define PI  3.14159265
#define N   256


void main()
{
  int i,n,mi,ma;
  float x[300],y[300],g[300];
  char ch[50];
  void draw(float data[],int num,int ratio,char ch[]);
  void Cov(float g[],float x[],float y[],int xb,int xe,int yb,int ye);
  int max(int a,int b);
  int min(int a,int b);
    for(i=0;i<300;i++)
    {
     x[i]=0;y[i]=0;g[i]=0;
    }

   for(i=0;i<100;i++)
    {
     x[i]=1;
    }

   for(i=0;i<200;i++)
    {
     y[i]=1;
    }
Cov(g,x,y,0,100,0,200);  
sprintf(ch,"x[n]");
draw(x,100,50,ch);
sprintf(ch,"y[n]");
draw(y,200,50,ch);
sprintf(ch,"x[n]*y[n]");
draw(g,300,1,ch);

}


int max(int a,int b)
{
  int c;
  c=a>b?a:b;
  return c;
}

int min(int a,int b)
{
 int c;
 c=a<b?a:b;
 return c;
}
void Cov(float g[],float x[],float y[],int xb,int xe,int yb,int ye)
{
   int i,n,mi,ma;
   for(n=xb+yb;n<=(xe+ye);n++)
	{
	 ma=max(xb,n-ye);
	 mi=min(xe,n-yb);
	 g[n]=0;
	   for(i=ma;i<=mi;i++)
		{
		  g[n]=g[n]+x[i]*y[n-i];
		}
	}
}
void draw(float data[],int num,int ratio,char ch[])
{
  int i,xb,xe,yb,ye,oy;
  int gdriver = DETECT,gmode;
  char buff[50];

  initgraph(&gdriver,&gmode,"d:\\tc30\\bgi");
  cleardevice();
  setbkcolor(0);  //set the  background black
  setcolor(30);  //set the axis yellow
  xb=50;xe=630;yb=50; ye=450; oy=(yb+ye)/2;

  outtextxy((xb+xe)/2,yb,ch);
  line(xb,oy,xe,oy);  //draw x axis
  outtextxy(xe,oy-2,">");
  outtextxy(xe-5,oy+3,"n");

  line(xb,yb,xb,ye);  //dray Y axis
  outtextxy(xb-3,yb-2,"^");
  outtextxy(xb+3,yb-2,"X(n)");


  for(i=0;i<3;i++)
  {
   line(xb,oy-i*50,xb+3,oy-i*50);
   sprintf(buff,"%d",i);
   outtextxy(xb-10,oy-i*50,buff);
   }


	for(i=0;i<101;i++)
  {
	if(i==10*int(i/10))
	 {
		line(xb+i*5,oy+5,xb+i*5,oy);
		sprintf(buff,"%d",i);
		if(i!=0)
		outtextxy(xb+i*5-5,oy+10,buff);
	 }
  }


  for(i=1;i<num;i++)
  {

	setcolor( 12);
	line(xb+(i-1),oy-data[i-1]*ratio,xb+i,oy-data[i]*ratio);
  }


  getchar();
  closegraph();

}