fir低通滤波程序，用C语言实现

/* ********************************************************************************** * Description ：对信号进行FIR滤波 * * Arguments ：fs[num]-- the data to be filtered ,num -- the dimension of data0[] * length -- the length of FIR filter ==20,so the order of the filter equals length-1 ==19 * * Return ：NO ********************************************************************************** */ extern void FIRfilter( double *fs,uint16 num,uint16 length) { uint16 i,j,win; double sum; //这样定义数组fp32 *x好像不行 double h[20] ={ 0.0076,0.0101,0.0170,0.0278,0.0412, 0.0559,0.0701,0.0825,0.0915,0.0963, 0.0963,0.0915,0.0825,0.0701,0.0559, 0.0412,0.0278,0.0170,0.0101,0.0076 }; win=num-length; for(i=0;i<num;i++) x1[i] = fs[i]; for(i=0;i<num;i++) { sum=0.0; for(j=0;j<length;j++) { if(i >= j) sum+=h[j]*x1[i-j]; else ; } fs[i]=sum; } for(i=0;i<NUM;i++) x1[i]=0.0; //数组复位，其实不需要的，只是习惯了 for(i=0;i<win;i++) { fs[i] = fs[i+length]; //考虑到前20个点为不完全累加和，故抛去前20个点。 } }