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mike.smartcam · Posted: Wed Dec 03, 2014 4:19 pm Post subject: Array variables

The following code was originally written for the Watcom compiler and I assume worked ok:

PaulLaidler · Posted: Wed Dec 03, 2014 5:43 pm Post subject:

No, the code looks like it has been corrupted.
Look for the places where HP is used (presumably without indexes).
If HP is an array then it needs a DIMENSION and its indexes ought to be integer values.
My guess is that it will be used as a scalar and that it should appear as a scalar in the assignment.

LitusSaxonicum · Posted: Wed Dec 03, 2014 10:29 pm Post subject:

Mike,

There has been a similar discussion recently here:

http://forums.silverfrost.com/viewtopic.php?t=2955

There is a chance that your HP is a statement function. It is a bit unusual that there is a PRINT first, but Watcom is a law unto itself, and perhaps HP means 'hypotenuse' or 'hypotenuse (by) Pythagorus' L1 and L2 are DOUBLE PRECISION so unlikely to be array subscripts, don't you agree?

Eddie

mecej4 · Joined: 31 Oct 2006 Posts: 1886

Indeed, HP appears to be a "statement function". One could guess that someone trying to troubleshoot the program added a print statement at the beginning of the subroutine executable statements, but made a slip.

Just move the PRINT statement down one line (blank lines do not count).

davidb · Joined: 17 Jul 2009 Posts: 560 Location: UK

Statement function for calculating a hypotenuse. Just move the print statement as suggested.

With all these kinds of errors you can get a list of what variables are in the code using /LIST /DUMP. This will produce a listing file showing you that it is a function not a variable.

There was a time when obtaining a variable dump with the code listing was a standard procedure but it seems to not be a popular debugging technique now.
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Programmer in: Fortran 77/95/2003/2008, C, C++ (& OpenMP), java, Python, Perl

John-Silver · Joined: 30 Jul 2013 Posts: 1520 Location: Aerospace Valley

I'm completely confused as to why you all want to move the PRINT statement down 1 line !
It's just there to say 'Here starteth the routine' , probably writing to the ternìminal in the good old days of screen and file output.
Keep it where it is I say.
Need to trace where the function is defined though :O)

JohnCampbell · Joined: 16 Feb 2006 Posts: 2554 Location: Sydney

The statement function HP = must proceed executable statements

PaulLaidler · Posted: Fri Dec 05, 2014 9:04 am Post subject:

John-Silver

The point is that this is the definition of the function HP.
It is old Fortran that is depreciated but still works.

mecej4 · Joined: 31 Oct 2006 Posts: 1886

The confusion expressed by John Silver reinforces the wisdom of the Fortran 95 standard's authors, when they say (in Section B.2 Obsolescent features: B.2.3, Statement functions):

mike.smartcam · Posted: Fri Dec 05, 2014 1:41 pm Post subject:

Thanks to everyone for the information
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Regards

Mike

mecej4 · Joined: 31 Oct 2006 Posts: 1886

Just to clear any incorrect conclusions that could be reached from what has been written in this thread, I installed the OpenWatcom F77 compiler on Win32, and ran it on the code posted by Mike.Smartcam. It said:

LitusSaxonicum · Posted: Fri Dec 05, 2014 6:11 pm Post subject:

If non-intuitiveness is the criterion to discard anything, perhaps we should dispense with most programming languages!

In my view, part of the problem is that as a language that occupies a specialist niche, Fortran isn't taught anymore, and computer science bookshelves aren't full of books on it (like McCracken or Etter), most people who program in it are largely or wholly self-taught, and some worthy programs were in any case written to match the facilities of a particular computer and compiler that now only exists in museums. Slef-teaching is an important part of learning, but it often results in an incomplete knowledge of a particular subject.

There isn't the slightest bit of non-intuitiveness about the local definition of an inline function with its scope limited to the routine it is defined in. I know that sooner or later I may fall over the definition of a statement function, which is why I would always add a comment or two explaining what it is and does.

Incidentally, what is the assumed type of the result of a statement function if IMPLICIT NONE is in use. I imagine that this is an obstacle to its use in recent-standard compliant use.

Eddie

mecej4 · Joined: 31 Oct 2006 Posts: 1886

LitusSaxonicum · Posted: Fri Dec 05, 2014 10:55 pm Post subject:

Would that be

JohnCampbell · Joined: 16 Feb 2006 Posts: 2554 Location: Sydney

If there is a problem with statement functions and so they were made obsolete, then why were contained functions introduced ? Surely the confusion about scope of variables in a statement function is very similar to that for a contained subroutine of function.