Go to the documentation of this file.00001 subroutine cffti1 (n,wa,ifac)
00002 dimension wa(*) ,ifac(*) ,ntryh(4)
00003 data ntryh(1),ntryh(2),ntryh(3),ntryh(4)/3,4,2,5/
00004 nl = n
00005 nf = 0
00006 j = 0
00007 101 j = j+1
00008 if (j-4) 102,102,103
00009 102 ntry = ntryh(j)
00010 go to 104
00011 103 ntry = ntry+2
00012 104 nq = nl/ntry
00013 nr = nl-ntry*nq
00014 if (nr) 101,105,101
00015 105 nf = nf+1
00016 ifac(nf+2) = ntry
00017 nl = nq
00018 if (ntry .ne. 2) go to 107
00019 if (nf .eq. 1) go to 107
00020 do 106 i=2,nf
00021 ib = nf-i+2
00022 ifac(ib+2) = ifac(ib+1)
00023 106 continue
00024 ifac(3) = 2
00025 107 if (nl .ne. 1) go to 104
00026 ifac(1) = n
00027 ifac(2) = nf
00028 tpi = 6.28318530717959
00029 argh = tpi/dble(n)
00030 i = 2
00031 l1 = 1
00032 do 110 k1=1,nf
00033 ip = ifac(k1+2)
00034 ld = 0
00035 l2 = l1*ip
00036 ido = n/l2
00037 idot = ido+ido+2
00038 ipm = ip-1
00039 do 109 j=1,ipm
00040 i1 = i
00041 wa(i-1) = 1.
00042 wa(i) = 0.
00043 ld = ld+l1
00044 fi = 0.
00045 argld = dble(ld)*argh
00046 do 108 ii=4,idot,2
00047 i = i+2
00048 fi = fi+1.
00049 arg = fi*argld
00050 wa(i-1) = cos(arg)
00051 wa(i) = sin(arg)
00052 108 continue
00053 if (ip .le. 5) go to 109
00054 wa(i1-1) = wa(i-1)
00055 wa(i1) = wa(i)
00056 109 continue
00057 l1 = l2
00058 110 continue
00059 return
00060 end
1.7.1
