线性卷积与循环卷积比较c程序 [复制链接]

#include<stdio.h>
#include<math.h>
#include<stdlib.h>
const int L1=4;
const int L2=6;
//普通线性卷积
void conv(float x[],int m,float y[],int n,float z[],int l)
{
        int i,j;
        for(i=0; i<l; i++)
        {
                z=0.0;
                for(j=0; j<n; j++)
                        if(i-j>=0&&i-j<=m-1)
                                z+=y[j]*x[i-j];
        }
}
//圆周移位,x1-原始有限长序列,x2-移位后的有限长序列,m-移动长度(>0右移,<0左移)
void CircleMove(float x1[],float x2[],int m,int num)
{
        int rr;
        for(int i=0; i<num; i++)
        {
                x2=0.0;
                rr=(i-m)%num;
                if(r>=0)
                    x2=x1[rr];
                else
                    x2=x1[num+rr];
        }
}
//时域圆周卷积,两等长序列x,y圆周卷积后得到z
//三序列长度都是num
void CircleConvolution(float x[],float y[],float z[],int num)
{
        float *y1,t;
        int i,j;
        y1=(float *)calloc(num,sizeof(float));
        for(i=1; i<=num/2; i++)
        { t=y;y=y[num-i];y[num-i]=t;}
        for(j=0; j<num; j++)
        { z[j]=0.0;
          CircleMove(y,y1,j,num);
          for(i=0; i<num; i++)
                  z[j]+=x*y1;
        }
        free(y1);
}

void main()
{
        float x[L1]={1,1,1,1};
        float y[L2]={1,1,1,1,1,1};
        float z1[L1+L2-1],z2[L1+L2-1];
        //直接线性卷积
    conv(x,L1,y,L2,z1,L1+L2-1);

        //要使循环卷积与线性卷积的结果相同，首先要将x,y的
    //长度扩大为L1+L2-1
        float *x1,*y1;
        x1=(float *)calloc(L1+L2-1,sizeof(float));
        y1=(float *)calloc(L1+L2-1,sizeof(float));
        for(int i=0; i<L1; i++)
                x1=x;
        for(i=0; i<L2; i++)
                y1=y;
        CircleConvolution(x1,y1,z2,L1+L2-1);
        printf("线性卷积:       圆周卷积:\n");
        for(i=0; i<L1+L2-1; i++)
             printf("z1[%d]=%f        z2[%d]=%f\n",i,z1,i,z2);
        free(x1);free(y1);
}
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