normal.c

speech signal process tools

normal(R,a,p,n)
	/* rtflag=1 if singular, rtflag=2 if non-pos-definite */
double R[],a[],p[];
register int n;
{
	register int i,j,ss,s,iM;
	int rtflag;
	register double ci,po,pf,temp;

	rtflag=0;

	for(i=0,iM=0;i<n;i++,iM+=n)
		{
		a[iM]=1;
		for(j=i+1;j<n;j++)
			a[iM+j]=0;
		}
	p[0]=R[0];
	for(i=1,s=n;i<n;i++,s+=n)
		{
		ss=s-n;
		ci=R[i];
		for(j=1;j<i;j++)
			ci+= a[ss+j]*R[i-j];
		if((po=p[i-1])==0)return(1);
		ci= -ci/po;
		if(ci<-1 || ci>1)
			rtflag++;
		a[s+i]=ci;
		for(j=1;j<i;j++)
			{
			temp=a[ss+j]+ci*a[ss+i-j];
			a[s+j]=temp;
			}
		pf=(1-ci*ci)*po;
		p[i]=pf;
		if(pf==0)return(1);
		}
	if(rtflag>0)return(2);
	return(0);
}