GNU Octave
4.4.1
A high-level interpreted language, primarily intended for numerical computations, mostly compatible with Matlab
cffti1.f
Go to the documentation of this file.
1
subroutine
cffti1
(n,wa,ifac)
2
dimension
wa(*) ,ifac(*) ,ntryh(4)
3
data
ntryh(1),ntryh(2),ntryh(3),ntryh(4)/3,4,2,5/
4
nl = n
5
nf = 0
6
j = 0
7
101 j = j+1
8
if
(j-4) 102,102,103
9
102 ntry = ntryh(j)
10
go to
104
11
103 ntry = ntry+2
12
104 nq = nl/ntry
13
nr = nl-ntry*nq
14
if
(nr) 101,105,101
15
105 nf = nf+1
16
ifac(nf+2) = ntry
17
nl = nq
18
if
(ntry .ne. 2)
go to
107
19
if
(nf .eq. 1)
go to
107
20
do
106 i=2,nf
21
ib = nf-i+2
22
ifac(ib+2) = ifac(ib+1)
23
106
continue
24
ifac(3) = 2
25
107
if
(nl .ne. 1)
go to
104
26
ifac(1) = n
27
ifac(2) = nf
28
tpi = 6.28318530717959
29
argh = tpi/dble(n)
30
i = 2
31
l1 = 1
32
do
110 k1=1,nf
33
ip = ifac(k1+2)
34
ld = 0
35
l2 = l1*ip
36
ido = n/l2
37
idot = ido+ido+2
38
ipm = ip-1
39
do
109 j=1,ipm
40
i1 = i
41
wa(i-1) = 1.
42
wa(i) = 0.
43
ld = ld+l1
44
fi = 0.
45
argld = dble(ld)*argh
46
do
108 ii=4,idot,2
47
i = i+2
48
fi = fi+1.
49
arg = fi*argld
50
wa(i-1) = cos(arg)
51
wa(i) = sin(arg)
52
108
continue
53
if
(ip .le. 5)
go to
109
54
wa(i1-1) = wa(i-1)
55
wa(i1) = wa(i)
56
109
continue
57
l1 = l2
58
110
continue
59
return
60
end
cffti1
subroutine cffti1(n, wa, ifac)
Definition:
cffti1.f:2
dimension
OCTAVE_EXPORT octave_value_list etc The functions then dimension(columns)
liboctave
external
fftpack
cffti1.f
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1.8.14