topic Thanks for the more complete in Intel® Fortran Compiler

Intrinsic Function HUGE result is 0.0

Ed_Martin — Tue, 10 Oct 2017 18:49:03 GMT

I am use Intel Fortran XE 17 update 4

Previously the following code sets the real variable to a very large negative value

real :: no_lower = -HUGH(1.0)

Now the variable is set to zero. Did something change in the Fortran standard?

Thanks for your help.

Did you actually write HUGH

Steve_Lionel — Tue, 10 Oct 2017 19:19:20 GMT

Did you actually write HUGH or HUGE? I get the correct value (in version 18) with HUGE.

Please show a short but complete example that demonstrates the problem, the compilation command you used and the output.

If he actually write "HUGH",

mecej4 — Tue, 10 Oct 2017 19:34:00 GMT

If he actually wrote "HUGH", that would be a non-standard function, and the linking of the program would have failed, unless there was a function called HUGH in the user's code or in some library provided by the user. Therefore, it is mysterious how the program could have been compiled, linked and run to the point where it produced output, erroneous as that output might have been!

I actually used HUGE(1.0).

Ed_Martin — Tue, 10 Oct 2017 19:37:15 GMT

I actually used HUGE(1.0). Sorry for the typo.

I figured as much - and yes,

Steve_Lionel — Tue, 10 Oct 2017 20:00:56 GMT

I figured as much - and yes, HUGH would have triggered multiple errors. Please show an example that demonstrates the problem.

Here's a program that

Ed_Martin — Wed, 11 Oct 2017 11:22:10 GMT

Here's a program that demonstrates the issue:

! T_HUGE.f90
!
! FUNCTIONS:
! T_HUGE - Entry point of console application.
!

!****************************************************************************
!
! PROGRAM: T_HUGE
!
! PURPOSE: Entry point for the console application.
!
!****************************************************************************

program T_HUGE

implicit none

    ! Variables
    real :: no_upper_limit = HUGE(1.0)
    real :: no_lower_limit = -HUGE(1.0)

    ! Body of T_HUGE
    print *, 'Hello World'
    print *, 'no_upper_limit =', no_upper_limit
    print *, 'no_lower_limit =', no_lower_limit

    print *,'<press return to end>'
    read *

end program T_HUGE

Command line:

/nologo /debug:full /Od /warn:interfaces /fpconstant /module:"Debug\\" /object:"Debug\\" /Fd"Debug\vc150.pdb" /traceback /check:bounds /check:stack /libs:dll /threads /dbglibs /c

Output:

Hello World
no_upper_limit = 3.4028235E+38
no_lower_limit = 0.0000000E+00
<press return to end>

The critical option is /fpconstant. Without it the no_lower_limit = -3.4028235E+38

Thanks for the more complete

Steve_Lionel — Wed, 11 Oct 2017 13:41:25 GMT

Thanks for the more complete information. That's a compiler bug, still present in 18. Please report it to Intel using the Online Service Center.

In the meantime I would recommend against using /fpconstant - this option should be avoided anyway as it papers over nonportable and nonstandard code.