I need to develop a library that opens a file and parses the stuff.
The unit number, due to fortran IO style, must be decided by me, but I can't know what other units are open in the client code. Is there a standard function like give_me_any_unit_number_that_is_free() ?
In fortran 2008, there's a newunit clause to open that you can use
integer :: myunit
..
open(newunit=myunit,file='file.dat')
...
close(myunit)
but that's new enough that not all compilers support it yet. If yours doesn't yet, you can mock one up yourself; there's a good example on the fortran wiki.
You can use INQUIRE to find a unit number that is not in use:
integer*4 function get_file_unit (lu_max)
!
! get_file_unit returns a unit number that is not in use
integer*4 lu_max, lu, m, iostat
logical opened
!
m = lu_max ; if (m < 1) m = 97
do lu = m,1,-1
inquire (unit=lu, opened=opened, iostat=iostat)
if (iostat.ne.0) cycle
if (.not.opened) exit
end do
!
get_file_unit = lu
return
end function get_file_unit
Related
I have been working with some old legacy code in Fortran used by a colleague. The actual code is proprietary, so the examples I use here are abbreviated compared to the code I'm working with.
Some of the procedures individually defined in *.f files included a file called variables.h:
Example contents of variables.h:
c VARIABLE DIMENSIONS FOR MODEL
c height_dim -- number of vertical (z) steps
c length_dim -- number of horizontal (x) steps
c width_dim -- number of horizontal (y) steps
INTEGER height_dim, length_dim, width_dim, nmodes, styleFlag
PARAMETER (height_dim=80, length_dim=50, width_dim=40)
PARAMETER (nmodes = 4,
$ styleFlag = 3)
I changed that to the following:
! VARIABLE DIMENSIONS FOR MODEL
! height_dim -- number of vertical (z) steps
! length_dim -- number of horizontal (x) steps
! width_dim -- number of horizontal (y) steps
INTEGER height_dim, length_dim, width_dim, nmodes, styleFlag
PARAMETER (height_dim=80, length_dim=50, width_dim=40)
PARAMETER (nmodes = 4, styleFlag = 3)
An example routine that uses these might be the following, called initial_conditions.f:
c This sets up the PDE's initial conditions
subroutine initial_conditions( temperature, density )
IMPLICIT NONE
INCLUDE 'variables.h'
real*8 temperature(height_dim,length_dim,width_dim)
real*8 density(height_dim)
temperature = 273.15D0
density = 1.0D0
return
end
I tried to compile a test routine written in F90 (or newer?) that included dimensions.h, but the compiler didn't like the fixed-form comments being included into the free-form *.f90 source file, so I changed all comments from c to !. Then I was able to compile my test program successfully. Let's call it test.f90:
program test
implicit none
include 'variables.h'
real*8, dimension(height_dim,length_dim,width_dim) :: vx, vy, vz
! <<Initialize data...>>
! << Output data...>>
end program test
Unfortunately, now the original code doesn't compile. It seems that code doesn't like commented lines to begin with ! (based on the fact that that was all I changed), but the actual errors it gives are the following:
variables.h(8): error #5082: Syntax error, found END-OF-STATEMENT when expecting one of: =
PARAMETER (nmodes = 4, styleFlag = 3)
------------------------------------------^
variables.h(5): error #6219: This variable, used in a specification expression, must be a dummy argument, a COMMON block object, or an object accessible through host or use association. [NMODES]
INTEGER height_dim, length_dim, width_dim, nmodes, styleFlag
---------------------------------------------^
What in the world is going on, and how can it be fixed?!
I imagine that comment styles are incompatible (free-form fortran thinks c is a variable, not a comment?), but I have no idea how it would produce these errors.
I'm sorry if this has been asked before, but I couldn't find an answer that seemed to work for me. I'm working with an old program, but have made a few modifications to it.
I can include the whole 2500 line program, but it seems like that is a lot.
I've successfully compiled the a program, but it fails when I try and run it. I'm getting a "Fortran runtime error: End of file" at the line which reads the .dat file. I've tried to compile a test segment, using the same .dat file and same variables. It results in the same problem.
PROGRAM OPEN
INTEGER (KIND=1), PARAMETER :: dy=3 ! number of income states
INTEGER (KIND=2) :: OpenStatus
REAL, DIMENSION(dy) :: grid,wt
OPEN(1,file='cygdrive/user/mk.dat',status='old',form='formatted',IOSTAT=OpenStatus)
READ (1,*) grid, wt
IF(OpenStatus>0) STOP 'cannot open mk.dat'
CLOSE(1)
PRINT*, grid(1)
END PROGRAM
The data file referenced is:
-1.7320508e+000
0.0000000e+000
1.7320508e+000
4.1777138e-001
1.6710855e+000
4.1777138e-001
Where each of these numbers is on its own line and preceeded by a space
This generates the same end of file runtime error. I'd really appreciate any help here.
I should add that I compiled with gfortran.
EDIT:
As per High Performance Mark's suggestion below, I've modified it to include an inquire test.
PROGRAM TEST
CHARACTER :: fnm, seq, fort
Logical :: lex
INTEGER (KIND=1), PARAMETER :: dy=3 ! number of income states
INTEGER (KIND=2) :: j,j0,j1,j2,j4,j5,j6,j7,k,jjj,jj,dyy,OpenStatus
REAL, DIMENSION(dy) :: grid,wt
OPEN(1,file='cygdrive/user/mk.dat',status='old',form='formatted',IOSTAT=OpenStatus)
INQUIRE (1, EXIST=lex, NAME=fnm, SEQUENTIAL=seq, FORMATTED=fort)
PRINT*, 'Exists=',lex, ' Name=',fnm, ' Sequential=', seq, 'Formatted=', fort
READ (1,*) grid, wt
IF(OpenStatus>0) STOP 'cannot open mk.dat'
CLOSE(1)
PRINT*, grid(1)
END PROGRAM
The results of the inquire statement are:
Exists= T Name= Sequential=U Formatted=U
My understanding is that the File is found (i.e. exists is returned as true), is un-named and the format and sequential access are returned as unknown (as is direct which I included later). I've also checked the delimiter and padding which are coming back as unknown.
My beginner intuition is telling me that I should try and create a new data file by writing to it with a fortran program and that should solve the problem? Is that correct? If so is there a fundamental misunderstanding at play here i.e. is this a problem with data files from other sources?
Thanks for all your patience.
(Answered in the comments. See Question with no answers, but issue solved in the comments (or extended in chat) )
The OP wrote:
I've fixed this problem-the program was looking for it in a different place, I've now corrected that.
On internet, I found this program that demonstrate Evaluating elliptic integrals of first and second kinds (complete)
implicit none
real*8 e,e1,e2,xk
integer i, n
e=1.d-7
print *,' K K(K) E(K) STEPS '
print *,'------------------------------------------'
xk=0.d0
do i = 1, 20
call CElliptic(e,xk,e1,e2,n)
write(*,50) xk,e1,e2,n
xk = xk + 0.05d0
end do
print *,'1.00 INFINITY 1.0000000 0'
stop
50 format(' ',f4.2,' ',f9.7,' ',f9.7,' ',i2)
end
Complete elliptic integral of the first and second kind. The input parameter is xk, which should be between 0 and 1. Technique uses Gauss' formula for the arithmogeometrical mean. e is a measure of the convergence accuracy. The returned values are e1, the elliptic integral of the first kind, and e2, the elliptic integral of the second kind.
Subroutine CElliptic(e,xk,e1,e2,n)
! Label: et
real*8 e,xk,e1,e2,pi
real*8 A(0:99), B(0:99)
integer j,m,n
pi = 4.d0*datan(1.d0)
A(0)=1.d0+xk ; B(0)=1.d0-xk
n=0
if (xk < 0.d0) return
if (xk > 1.d0) return
if (e <= 0.d0) return
et n = n + 1
! Generate improved values
A(n)=(A(n-1)+B(n-1))/2.d0
B(n)=dsqrt(A(n-1)*B(n-1))
if (dabs(A(n)-B(n)) > e) goto et
e1=pi/2.d0/A(n)
e2=2.d0
m=1
do j = 1, n
e2=e2-m*(A(j)*A(j)-B(j)*B(j))
m=m*2
end do
e2 = e2*e1/2.d0
return
end
I have compiled it but I have received the following errors:
gfortran -Wall -c "gauss.f" (nel direttorio: /home/pierluigi/Scrivania)
gauss.f:53.9:
50 format(' ',f4.2,' ',f9.7,' ',f9.7,' ',i2)
1
Error: Invalid character in name at (1)
gauss.f:83.72:
if (dabs(A(n)-B(n)) > e) goto et
1
Warning: Deleted feature: Assigned GOTO statement at (1)
gauss.f:83.35:
if (dabs(A(n)-B(n)) > e) goto et
1
Error: ASSIGNED GOTO statement at (1) requires an INTEGER variable
gauss.f:48.18:
write(*,50) xk,e1,e2,n
1
Error: FORMAT label 50 at (1) not defined
Compilation failed.
Any suggestions please?
EDIT
I have read all your answers and thanks to you I managed to compile the program. I also have another curiosity and I do not know whether to write another question. In the meantime I modify this question. In my program, xk is increased by 0.05. Now I will that the program to read data from a file containing: the minimum value of xk; the maximum value of xk; the number of intervals. I thought:
open (10,file='data/test')
read (10,*) xkmi, xkma
read (10,*) nk
close (10)
lkmi = dlog(xkmi)
lkma = dlog(xkma)
ldk = (lkma-lkmi)/dfloat(nk-1)
In addition, the program must be modified in such a way that the result is written to another file. How can I change the rest of the program? Thank you very much.
Your source code file extension is f which, I think (check the documentation), tells gfortran that the file contains fixed source form. Until Fortran 90 Fortran was still written as if onto punched cards and the location of various bits and pieces of a line is confined to certain columns. A statement label, such as 50 in the first of the error messages, had to be in columns 1 - 6. Two solutions:
Make sure the label is in (some of) those columns. Or, better
Move to free source form, perhaps by changing the file extension to f90, perhaps by using a compilation option (check your documentation).
The error raised by the goto et phrase is, as your compiler has told you, an example of a deleted feature, in which the goto jumps to a statement whose label is provided at run-time, ie the value of et. Either tell your compiler (check ...) to conform to an old standard, or modernise your source.
Fix those errors and, I suspect, the other error messages will disappear. They are probably raised as a consequence of the compiler not correctly parsing the source after the errors.
Because the file has type ".f" gfortan is interpreting it as fixed-source layout. Trying compiling with the free-form layout by using compiler option -ffree-form and see if that works. This probably explains the error about the "invalid character". That statement not being recognized explains the "format not defined error". The "computed goto" is obsolete but valid Fortran. You can ignore that warning. If you wish, later you can modernize the code. For the remaining error, for the "assigned goto", declare "et" as an integer.
I would just do this
10 n = n + 1
! Generate improved values
A(n)=(A(n-1)+B(n-1))/2.d0
B(n)=dsqrt(A(n-1)*B(n-1))
if (dabs(A(n)-B(n)) > e) goto 10
and possibly compile as free form source as others have shown. The label et seems weird and non-standard, possibly a rare vendor extension.
You could also change the lines above to a do-loop with an exit statement (Fortran 90).
(The program compiled for me after the change).
I tested the subroutine and compared with matlab and it was not the same. It is very similar to the algorithm used in Abramowitz's book. Here is the one I wrote that works well, just for comparing.
subroutine CElliptic(m,K,E)
implicit none
real*8 m,alpha,E,K,A,B,C,A_p,B_p,C_0,pi,suma
integer j,N
N=100
alpha=asin(sqrt(m))
pi = 4.d0*datan(1.d0)
A_p=1.0
B_p=cos(alpha)
C_0=sin(alpha)
suma=0.0
do j=1,N
A=(A_p+B_p)/2.0d0
B=dsqrt(A_p*B_p)
C=(A_p-B_p)/2.0d0
suma=suma+2**(j)*C**2
A_p=A
B_p=B
end do
K=pi/(2*A)
E=(1-1.d0/2.d0*(C_0**2+suma))*K
end Subroutine CElliptic
best regards
Ed.
I've recently started working on an existing Fortran program, and picking up the language at the same time. I wrote the following subroutine:
subroutine timing(yyyy, mm, dd, var, ntime, time_blocks,
* time_day)
use myglobals
! ---------------------------------------------------------------------
! Common Variables
! ---------------------------------------------------------------------
integer yyyy, ! year
* mm, ! month
* dd, ! day
* ntime ! nr of blocks for which time was measured
real time_blocks(ntime),
* time_day
character*4 var
! ---------------------------------------------------------------------
! Internal Variables
! ---------------------------------------------------------------------
integer ios
integer out_unit=52
open(unit=out_unit, file=diroutput(1:69)//'timing',
* err=450, iostat=ios)
450 print*, "iostat= ", iostat
print*, "open"
write(out_unit, format_str) yyyy, mm, dd, var, time_blocks,
* time_day
return
end
The purpose of this subroutine is to write the inputs it gets from another part of the program to a file, following a defined format (format definition not included in my example). The file must be created on the first call of this subroutine, then accessed on each further call in order to append the new information. diroutput is a character string defined in myglobals.
My problem is that the program seems to get hung up at the OPEN statement, i.e. nothing happens until I kill the process. I ran the code with several print*, statements to locate the error, and found out this way that the error must be in the OPEN statement. It seems strange that the program does nothing at all, not even jump to the error label.
As I'm new to Fortran I might be missing something fairly obvious, so a quick look by someone more experienced might help. I'm certain that diroutput contains a valid path.
I'm using Linux (CentOS 5.5) and I compiled my program with Intel Fortran Compiler 11.1.
Your code seems, from the continuation characters in (generally) column 6, to be written in fixed-form despite containing features of Fortran 90. If it is fixed-form then statement labels, such as 450 should be in columns 1 to 5. I don't immediately see why that would cause the program to hang rather than crash, but I suggest you fix this and try again.
How can I copy a file in fortran 90 in a portable, cross plaform way ?
Use the SYSTEM with your OS's copy command. Practically all compilers support this feature.
You can read/write the file through a stream in Fortran 2003, but in Fortran 90/95 I think this would work to copy an arbitrary file (extremely inefficient though!!)
OPEN(UNIT=ISRC, FILE='', ACCESS='DIRECT', STATUS='OLD', ACTION='READ', IOSTAT=IERR, RECL=1)
OPEN(UNIT=IDST, FILE='', ACCESS='DIRECT', STATUS='REPLACE', ACTION='WRITE', IOSTATE=IERR, RE)
IREC = 1
DO
READ(UNIT=ISRC, REC=IREC, IOSTAT=IERR) CHAR
IF (IERR.NE.0) EXIT
WRITE(UNIT=IDST, REC=I) CHAR
IREC = IREC + 1
END DO
Of course, if it was a fortran generated file, you could use that information to make it more efficient.
On a personal note: if you need invoke system calls from inside fortran, what are you doing? Isn't it better to use some other language that is better suited for the task?
Yes, Fortran has pathetic I/O and shouldn't be used for this sort of thing if at all possible. What a shame that some of us are forced to do it.
I just read the source file and simultaneously write to the destination, line-by-line. So far this works for me, but is very inefficient.
Dealing with files and portability is annoying with Fortran, and SYSTEM calls are often not very good either. The windows OS doesn't properly follow linux linked files, and Windows/Linux/MacOS have different separaters, I have been caught out with stack limits inherent in the SYSTEM call, and so on.
Good luck !
For Intel Fortran
subroutine copy_file (file_name, file_name_new)
! copies a file file_name to file_name_new
! file_name and file_name_new must include the path information and may include wildcard characters
USE ifport
implicit character*100 (f)
character*1000 fnam
logical*4 logical_result
len1 = len_trim(file_name); len2 = len_trim(file_name_new)
fnam = 'copy/y ' //file_name(1:len1) //' '//file_name_new(1:len2)
l = len_trim(fnam)
logical_result = systemqq(fnam(1:l))
return
end
The previous answer didn't work for me so I wrote the following subroutine
!=============================================================================================================================!
! !
! This subroutine copies file_name to file_name_new writing command to cmd !
! !
!=============================================================================================================================!
subroutine copy_file (file_name, file_name_new)
use ifport
implicit none
!=============================================================================================================================
! D e c l a r a t i o n s
!=============================================================================================================================
character(len=*),intent(IN) :: file_name_new,file_name
!-----------------------------------------------------------------------------------------------------------------------------
logical :: logical_result
!=============================================================================================================================
! S t a t e m e n t s
!=============================================================================================================================
logical_result = systemqq('copy "'//trim(file_name) //'" "'//trim(file_name_new)//'"')
!==============================================================================================================================
end subroutine copy_file
! For Compaq/Intel Visual Fortran
subroutine copy_file(source_,dest_)
use kernel32,only:CopyFile,FALSE
implicit none
integer ret
character*(*), intent(in) :: source_, dest_
ret = CopyFile(trim(source_)//""C, trim(dest_)//""C, FALSE)
end subroutine copy_file