设计巴特沃斯模拟低通滤波器求转移函数
设计巴特沃斯模拟低通滤波器，求出转移函数G(p)subroutine butwcf(l,k,ln,d,c,ierror)
c----------------------------------------------------------------------
c routine BUTWCF: To design low-pass Butterworth analog filter:
c H(s)=D(s)/C(s) ,
c If IERROR=0: no errors detected
c =1: invalid filter order l and k
c in Chapter 7
c----------------------------------------------------------------------
dimension d(0:4),c(0:4)
pi=4.*atan(1.)
ierror=1
if(l.le.0.or.k.gt.int((l+1)/2)) return
ierror=0
d(0)=1.
c(0)=1.
do 10 i=1,ln
d(i)=0.
c(i)=0.
10 continue
orderk=k-(l+1.)/2.
if(orderk.eq.0) goto 20
c(1)=(-2.)*cos((2*k+l-1)*pi/(2*l))
c(2)=1.
return
20 c(1)=1.
return
end
[ 本帖最后由 VibInfo 于 2006-8-6 07:26 编辑 ]
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