1 c===========================================================================
3 c This file is part of TISEAN
5 c Copyright (c) 1998-2007 Rainer Hegger, Holger Kantz, Thomas Schreiber
7 c TISEAN is free software; you can redistribute it and/or modify
8 c it under the terms of the GNU General Public License as published by
9 c the Free Software Foundation; either version 2 of the License, or
10 c (at your option) any later version.
12 c TISEAN is distributed in the hope that it will be useful,
13 c but WITHOUT ANY WARRANTY; without even the implied warranty of
14 c MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 c GNU General Public License for more details.
17 c You should have received a copy of the GNU General Public License
18 c along with TISEAN; if not, write to the Free Software
19 c Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
21 c===========================================================================
23 c autocorrelation function through FFT
24 c author T. Schreiber (1998), H. Kantz (2007)
25 c===========================================================================
29 character*72 file, fout
32 call whatido("autocorrelation function estimated by FFT",iverb)
36 if(iexact.ne.0) iper=1
40 isout=igetout(fout,iverb)
42 do 10 ifi=1,nstrings()
43 call nthstring(ifi,file)
45 call readfile(nmax,x,nexcl,jcol,file,iverb)
46 if(file.eq."-") file="stdin"
47 if(ivar.eq.0) call normal(nmax,x,sc,sd)
52 call store_spec(nmaxp,x,1)
54 30 x(n)=x(n)/real(nmax-n+1)
59 if(nmaxp.ne.nmax.and.iv_io(iverb).eq.1)
60 . write(istderr(),*) "autocor: using", nmaxp
62 call store_spec(nmaxp,x,1)
64 50 x(n)=x(n)/real(nmaxp)
66 if(isout.eq.1) call addsuff(fout,file,"_co")
67 call outfile(fout,iunit,iverb)
69 if(sd.eq.0) stop "autocor: cannot normalise - zero variance"
74 do 60 n=1,min(nmax,nmaxp)
75 60 write(iunit,*) n-1, fsc*x(n)
76 10 if(iunit.ne.istdout()) close(iunit)
83 . "[-v -p -P -o outfile -l# -x# -c# -V# -h] file(s)")
84 call popt("v","give unnormalised autocovariance")
85 call popt("p","assume periodic continuation")
86 call popt("P","assume periodic continuation exactly")
87 call popt("l","number of values to be read [all]")
88 call popt("x","number of values to be skipped [0]")
89 call popt("c","column to be read [1 or file,#]")