Help with Fortran90
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== Second approach: f2c ==
== Second approach: f2c ==
Using f2c gives the same results as using f77. I hoped to get more insight from reading the C-code, but I did not. I had big success for the other IMCCE fortran programs with
Using f2c gives the same results as using f77. I hoped to get more insight from reading the C-code, but I did not. I had big success for the other IMCCE fortran programs with , it helped me a lot in understanding and getting functional executables. But not this time.
== Summary ==
== Summary ==
Revision as of 22:22, 8 May 2007
This page is dedicated to conversation and mutual help on creating Neptunian satellite ephemeris using Le Guyader's and Jerome Berthier's ftp://ftp.imcce.fr/pub/ephem/satel/neptuno/
First approach: f77
In Config.mk replace FC = xlf with FC = f77 and type 'make'. You will see lots of errors like
isat_d.f: In subroutine `isatd': isat_d.f:1353: 210 format(8x,' Dernier pas:',d23.16)' ^ Invalid form for FORMAT statement at (^)
In my opinion the reason is that the code is not FORTRAN77 conform. I tried to overcome this problem by fixing the source code, there is an awful lot of wrong format statements. For finding the input files I changed in fs2fd.f:
infile = trim(dir_s)//trim(fil_s) outfile = trim(dir_d)//trim(fil_d)
infile = './data/Nsat-fs.dat' outfile = './data/Nsat-fd.dat'
Same in ins_d.f:
theofile = './data/Nsat-fd.dat'
Additionally in ins_d.f I had to move the passage
LOGICAL FIRST DATA FIRST/.TRUE./
after the COMMON block:
COMMON/STCOMX/KM,BARY,PVSUN LOGICAL FIRST DATA FIRST/.TRUE./
FORTRAN77 seem not to support variable size arrays, so in isat_d.f I had to replace
in line 183 with
The same for lines 2455 and 2456. In line 2408 I removed the definition of w(3,np,0:nd). After that the source compiled into an executable called 'ilgs_d', which is ought to be the double precision version. The quad precision version would be called 'ilgs_q'. Anyway, the executable failed with the following output:
________________________________________ Fichier ./data/Nsat-fd.dat ________________________________________ open: No such file or directory apparent state: unit 12 named /DATA/DE403/de403.unx last format: list io lately reading direct unformatted external IO Aborted
Second approach: f2c
Using f2c gives the same results as using f77. I hoped to get more insight from reading the C-code, but I did not. I had big success for the other IMCCE fortran programs with f2c, it helped me a lot in understanding and getting functional executables. But not this time.
The file ./data/Nsat-fd.dat exists, maybe the error refers to the file /DATA/DE403/de403.unx, which is indeed missing on my system. And I do not know from where to get it. At ftp://ssd.jpl.nasa.gov/pub/eph/planets/bsp/DE403.BSP I found the file for Sparc architecture, for i386 it seems not to be available any more, but it could be created from DE403.BSP.
But before doing further investigation I would like to ask a FORTRAN programmer about this software. My understanding is as follows, please correct me when I am wrong:
1) The software is a numerical integrator for a physical model of the Nepunian system. For as a period as long as the planet positions are provided, the Neptunian satellites position can be computed by numerical integration. Especially dates outside the interval 1800-2050 are no problem, when the DE403 planet positions are replaced by VSOP87 or similar.
2) Therefore it is possible to produce a large table of each satellites position and velocity for a long period, lets say 1500-2500. In fact this is the main goal. When I have this table, I will try frequency analysis techniques in order to create poisson series or similar, that can be included into stellarium.
My problem is that I can speak neigther french nor FORTRAN, so I really do not know what is going on in this software, and I would really appreciate your help. You can contact be by:
- posting into the forum
- writing something in this wiki page
Johannes 14:38, 1 May 2007 (PDT)
Hi! I'm a french programmer, but unfortunately not a fortran programmer, and I'd like to help if I can . I've started to read fortran tutorial and I plan to test lf95 trial as fortran compiler since it's the one used in the linux Config.mk provided in neptuno package but I don't have much free time these days. I'll let know if I succeed in any way, let me know if you have questions. Blakbear.