I'm working on some scientific code that is mostly F77 but also some F95. In places, I need to include F77 code into my F95 code. Is there a way to get this code to play nicely within my code by using a particular compiler flag or something? I'm using gfortran and occasionally ifort. It is possible for me to modify the legacy code but I would need to do it in a sensible way to maintain backwards compatibility with other F77 code while also being forwards compatible with F95 code.
I get errors like:
cstruc:16.12:
Included at mod_op.f90:6:
REAL*8
1
Error: Invalid character in name at (1)
cstruc:17.6:
Included at mod_op.f90:6:
& RH, RH1, ! ln rho
1
Error: Invalid character in name at (1)
cstruc:18.6:
Included at mod_op.f90:6:
& RHP, RHP1, ! d ln rho / d ln p
1
Error: Invalid character in name at (1)
cstruc:19.6:
Included at mod_op.f90:6:
& RHT, RHT1, ! d ln rho / d ln T
1
Error: Invalid character in name at (1)
cstruc looks like this:
REAL*8
& RH, RH1, ! ln rho
& RHP, RHP1, ! d ln rho / d ln p
& RHT, RHT1, ! d ln rho / d ln T
& PSI, ! ln Lambda (for degenerate gas)
& RHPSI, ! d ln rho / d PSI
& RHPSIP, ! d2 ln rho / d PSI d ln P
& RHPSIT, ! d2 ln rho / d PSI d ln T
& PL, ! P at J1
& TONI ! T at J1
Any help is much appreciated. Thanks!
With some exceptions, Fortran 77 code is Fortran 95 code. I guess that your errors come from that you are attempting to include fixed-form source code (your F77 code in cstruc) into a free-form source code file mod_op.f90. This is unlikely to end well.
Most compilers will assume a file ending in ".f90" is free-form, so if you really are using fixed-form then you will need a compiler flag to override the assumption.
It is possible to combine free- and fixed-form code into a final object (each compiled separately), but a good suggestion as to how to resolve the problems you are seeing can come only with more detail.
However, if you are attempting with your include to create a module to replace a common block, then there is no reason why you can't use the F95 feature with fixed-form. Just do that selectively.
Alternatively, you can see the answer by Vladimir F which explains how to write source code that is valid as both free-form and fixed-form source. You can use this to modify the Fortran 77 fixed-form code to be include-able by the Fortran 90 free-form code while still being compilable as fixed-form (but not valid Fortran 77).
I suggest to try the "intersection" form from http://fortranwiki.org/fortran/show/Continuation+lines
It is legal as both free and fixed source form.
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 need a procedure to calculate the incomplete Gamma function. Of course, I've tried the netlib route and found the dgamic function. However, after compiling the following test program
program test_dgamic
implicit none
interface
double precision function dgamic(in1,in2)
double precision, intent(in) :: in1,in2
end function dgamic
end interface
print *, 'dgamic:', dgamic(1.d0,1.d0)
end program test_dgamic
with gfortran version 6.2.0 like this
gfortran main.f90 -o main dgamic.f d9lgic.f d9lgit.f d9gmic.f d9gmit.f dlgams.f dlngam.f dgamma.f d9lgmc.f dcsevl.f dgamlm.f initds.f d1mach.f xerclr.f xermsg.f xerprn.f xersve.f xgetua.f i1mach.f j4save.f xerhlt.f xercnt.f fdump.f
and running, I get the following slatec error message
***MESSAGE FROM ROUTINE INITDS IN LIBRARY SLATEC.
***POTENTIALLY RECOVERABLE ERROR, PROG ABORTED, TRACEBACK REQUESTED
* Chebyshev series too short for specified accuracy
* ERROR NUMBER = 1
*
***END OF MESSAGE
***JOB ABORT DUE TO UNRECOVERED ERROR.
0 ERROR MESSAGE SUMMARY
LIBRARY SUBROUTINE MESSAGE START NERR LEVEL COUNT
SLATEC INITDS Chebyshev series too 1 1 1
Note: The following floating-point exceptions are signalling: IEEE_DIVIDE_BY_ZERO
Has anyone got a clue how to avoid this? From the looks of the error, it looks like a design flaw.
It seems that the problem is (again) due to d1mach.f in Slatec, because we need to uncomment an appropriate section of that file manually. In practice, it is more convenient to use a modified version of d1mach.f available from the BLAS site (see this page). So the procedure may be something like:
1) download slatec_src.tar.gz from the original site
2) download modified (BLAS) versions of d1mach.f etc and use them instead of the Slatec versions
rm -f i1mach.f r1mach.f d1mach.f
wget http://www.netlib.org/blas/i1mach.f
wget http://www.netlib.org/blas/r1mach.f
wget http://www.netlib.org/blas/d1mach.f
3) and comiple, e.g., with a test program
program main
implicit none
external dgamic
double precision dgamic, a, x, y
a = 1.0d0
x = 1.0d0
y = dgamic( a, x )
print *, "a = ", a
print *, "x = ", x
print *, "y(slatec) = ", y
print *, "y(exact for a=1) = ", exp( -x )
end program
which gives
a = 1.0000000000000000
x = 1.0000000000000000
y(slatec) = 0.36787944117144233
y(exact for a=1) = 0.36787944117144233
For comparison, if we use the Slatec version of d1mach.f, we get the same error
***MESSAGE FROM ROUTINE INITDS IN LIBRARY SLATEC.
***POTENTIALLY RECOVERABLE ERROR, PROG ABORTED, TRACEBACK REQUESTED
* Chebyshev series too short for specified accuracy
* ERROR NUMBER = 1
...
because the precision is not set in d1mach.f (we need to uncomment a necessary section, e.g. labeled as "IBM PC", plus some modifications for legacy Fortran, which could be tedious...)
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.
Im a very poor programmer, and i was given a program to supposedly help me on my aerodynamic hw. but its in fortran, and im trying to use MATLAB to run this program. any help on converting it to a language matlab understands? (preferabbly c++)
program joukow
c
c computes joukowski airfoil and finds pressure coefficient
c currently set up for symmetric airfoil with sharp trailing edge
c and chord length equal to one.
c profile is written onto prof.dat and cp onto cp.dat
c implicit real*8(a-h,o-z)
complex z,zeta,cw
dimension uz(100),vz(100),xi(100),eta(100),cp(100)
dimension xout(100),yout(100)
open(unit=8,file='prof.dat',status='unknown')
open(unit=9,file='cp.dat',status='unknown')
b=1.d0
write(6,98)
format(2x,'input the radius of the a-circle in z plane')
read(5,99)a
format(f10.0)
xl=2.*a-1.+1./(2.*a-1.)
c xl=a+1./a
c chord=2.*xl
chord=2.+xl
del=a-b
c del =0.1d0
do 50 i=1,100
ri=i
theta=6.2832d0*ri/101.d0
x=-del+a*cos(theta)
y=a*sin(theta)
z=cmplx(x,y)
zeta=z+b**2/z
c
c xi and eta are coordinates of points on airfoil
c
xi(i)=real(zeta)
eta(i)=aimag(zeta)
cw=(1.-a**2/(z+del)**2)/(1.-b**2/z**2)
c
c uz and vz are velocity components on the airfoil assuming the free-stream
c speed is one.
c
uz(i)=real(cw)
vz(i)=-aimag(cw)
c
c xout and yout are airfoil coordinates where the leading edge is at (0,0)
c and the chordlength is one.
c
xout(i)=(xl+xi(i))/chord
yout(i)=eta(i)/chord
write(8,100)xout(i),yout(i)
format(2x,2f10.4)
continue
c
c now calculate the pressure coefficient cp
c
write(6,200)
format(2x,'pressure coefficients')
do 70 i=1,50
cp(i)=1.-(uz(i)**2+vz(i)**2)
write(9,100)xout(i),cp(i)
continue
stop
end
Matlab understands Fortran just fine -- check the documentation. And if that doesn't satisfy you, most of the lines in the program which do any computation could be typed into the Matlab console with very little modification. If you are a poor programmer, I suggest that you spend your time modifying the program into Matlab rather than into C++. I'll write more later if you don't get any better help than I have time for right now.
EDIT: first off, some information on using Fortran source files from Matlab. If you really don't want to (or can't or have performance reasons for not doing so) rewrite the Fortran into Matlab then turn it into a MEX file. Using f2c (or anything else, including your own time and effort) to first translate the Fortran into C or C++ seems pointless to me.
If you don't like that idea, here are some ideas on turning Fortran into Matlab.
First, all lines beginning with C or c are comments so you don't need to translate them. Start with your code:
complex z,zeta,cw
dimension uz(100),vz(100),xi(100),eta(100),cp(100)
dimension xout(100),yout(100)
These lines declare a number of variables. You don't have to declare variables before you use them in Matlab but, there are sometimes good reasons to do so. You don't have to in Fortran either, though this is universally considered a bad idea these days. You could 'declare' these variables in Matlab with statements such as:
uz = zeros(100,1);
vz = zeros(100,1);
By declaring these in advance in your Matlab you allocate memory for them once, and avoid some performance-reducing problems.
The next 2 lines:
open(unit=8,file='prof.dat',status='unknown')
open(unit=9,file='cp.dat',status='unknown')
open a couple of files for output. They are used later in write statements - forget them, write Matlab statements such as save xout instead.
The next line is Fortran but identical in Matlab:
b=1.d0
The next lines get a value for the radius from the console:
write(6,98)
format(2x,'input the radius of the a-circle in z plane')
read(5,99)a
format(f10.0)
again, I suggest you forget these, just use the Matlab console to set the value of a. More Fortran that doesn't need to be translated (though I suggest you either drop the decimal points without following 0s or put a space between them and the subsequent * -- .* is a specific operator in Matlab):
xl=2.*a-1.+1./(2.*a-1.)
chord=2.+xl
del=a-b
A Fortran do loop is the same as a Matlab for loop. Rewrite:
do 50 i=1,100
as
for i = 1:100
As one of the other respondents has noted it's not clear where the matching end statement goes, you'll have to figure that out. Note that I'm just offering a line-by-line translation of Fortran into Matlab. It's not well-written Fortran, and I'm not offering well-written Matlab, I'll leave that to you.
This lot doesn't need to be translated:
ri=i
theta=6.2832d0*ri/101.d0
x=-del+a*cos(theta)
y=a*sin(theta)
cmplx is a Fortran function which returns a complex number which has real part x and imaginary part y:
z=cmplx(x,y)
In Matlab this would be z = x + y * i. Fortran uses ** for exponentiation, Matlab uses ^
zeta=z+b**2/z
and so on and so on.
Hope that helps.
I used f2matlab and a little touching up afterward. Here is the cleaned up and compilable fortran90 code:
program joukow
!
! computes joukowski airfoil and finds pressure coefficient
! currently set up for symmetric airfoil with sharp trailing edge
! and chord length equal to one.
! profile is written onto prof.dat and cp onto cp.dat
! implicit real*8(a-h,o-z)
complex z,zeta,cw
dimension uz(100),vz(100),xi(100),eta(100),cp(100)
dimension xout(100),yout(100)
open(unit=8,file='prof.dat',status='unknown')
open(unit=9,file='cp.dat',status='unknown')
b=1.d0
write(6,98)
98 format(2x,'input the radius of the a-circle in z plane')
read(5,99)a
99 format(f10.0)
xl=2.*a-1.+1./(2.*a-1.)
! xl=a+1./a
! chord=2.*xl
chord=2.+xl
del=a-b
! del =0.1d0
do i=1,100
ri=i
theta=6.2832d0*ri/101.d0
x=-del+a*cos(theta)
y=a*sin(theta)
z=cmplx(x,y)
zeta=z+b**2/z
!
! xi and eta are coordinates of points on airfoil
!
xi(i)=real(zeta)
eta(i)=aimag(zeta)
cw=(1.-a**2/(z+del)**2)/(1.-b**2/z**2)
!
! uz and vz are velocity components on the airfoil assuming the free-stream
! speed is one.
!
uz(i)=real(cw)
vz(i)=-aimag(cw)
!
! xout and yout are airfoil coordinates where the leading edge is at (0,0)
! and the chordlength is one.
!
xout(i)=(xl+xi(i))/chord
yout(i)=eta(i)/chord
write(8,100)xout(i),yout(i)
100 format(2x,2f10.4)
end do
!
! now calculate the pressure coefficient cp
!
write(6,200)
200 format(2x,'pressure coefficients')
do i=1,50
cp(i)=1.-(uz(i)**2+vz(i)**2)
write(9,100) xout(i),cp(i)
end do
stop
end program joukow
Here is the resulting matlab code:
function hw1(varargin)
%
% computes joukowski airfoil and finds pressure coefficient
% currently set up for symmetric airfoil with sharp trailing edge
% and chord length equal to one.
% profile is written onto prof.dat and cp onto cp.dat
% implicit real*8(a-h,o-z)
format_99=['%10.0f'];
format_100=[repmat(' ',1,2),repmat('%10.4f',1,2),'\n'];
format_200=[repmat(' ',1,2),'pressure coefficients \n'];
fid_8=fopen('prof.dat','w+');
fid_9=fopen('cp.dat','w+');
b=1.0d0;
a=input('input the radius of the a-circle in z plane');
xl=2..*a-1.+1../(2..*a-1.);
% xl=a+1./a
% chord=2.*xl
chord=2.+xl;
del=a-b;
% del =0.1d0
for i=1:100;
ri=i;
theta=6.2832d0.*ri./101.0d0;
x=-del+a.*cos(theta);
y=a.*sin(theta);
z=complex(x,y);
zeta=z+b.^2./z;
%
% xi and eta are coordinates of points on airfoil
%
xi(i)=real(zeta);
eta(i)=imag(zeta);
cw=(1.-a.^2./(z+del).^2)./(1.-b.^2./z.^2);
%
% uz and vz are velocity components on the airfoil assuming the free-stream
% speed is one.
%
uz(i)=real(cw);
vz(i)=-imag(cw);
%
% xout and yout are airfoil coordinates where the leading edge is at (0,0)
% and the chordlength is one.
%
xout(i)=(xl+xi(i))./chord;
yout(i)=eta(i)./chord;
fprintf(fid_8,format_100,xout(i),yout(i));
end; i=100+1;
%
% now calculate the pressure coefficient cp
%
fprintf(1,format_200);
for i=1:50;
cp(i)=1.-(uz(i).^2+vz(i).^2);
fprintf(fid_9,format_100, xout(i),cp(i));
end; i=50+1;
end %program joukow
They both give the same results for me. I didn't check the algorithm for correctness, though, just converted the code.
I don't know how well it's still supported - - but the easiest way used to be f2c which translates fortran directly into c code.