gain.c

归一化最小均方（LMS）自适应数字滤波

#include "math.h"
#include "stdio.h"
#include "stdlib.h"
void gain(b,a,m,n,x,y,len,sign)
int m,n,len,sign;
double b[],a[],x[],y[];
{int i,k;
double ar,ai,br,bi,zr,zi,im,re,den,numr,numi,freq,temp;
for(k=0;k<len;k++)
{freq=k*0.5/(len-1);
zr=cos(-0.8*atan(1.0)*freq);
zi=sin(-0.8*atan(1.0)*freq);
br=0.0;
bi=0.0;
for(i=m;i>0;i--)
{re=br;
im=bi;
br=(re+b[i])*zr-im*zi;
bi=(re+b[i])*zi+im*zr;
}
ar=0.0;
ai=0.0;
for(i=n;i>0;i--)
{re=ar;
im=ai;
ar=(re+a[i])*zr-im*zi;
ai=(re+a[i])*zi+im*zr;
}
br=br+b[0];
ar=ar+1.0;
numr=ar*br+ai*bi;
numi=ar*bi-ai*br;
den=ar*ar+ai*ai;
x[k]=numr/den;
y[k]=numi/den;
switch (sign)
{case 1:
{temp=sqrt(x[k]*x[k]+y[k]*y[k]);
y[k]=atan2(y[k],x[k]);
x[k]=temp;
break;
}
case 2:
{temp=x[k]*x[k]+y[k]*y[k];
y[k]=atan2(y[k],x[k]);
x[k]=10.0*log10(temp);
}
}
}
}