Extension to iso_fortran_env

Hello.

There does not appear to be support for ieee_arithmetic in the current ftn95 e.g.

program ieee
    use, intrinsic :: iso_fortran_env, only: wp=>real64
    use, intrinsic :: ieee_arithmetic
    implicit none

    print *, ieee_value(1.0_wp, ieee_positive_inf)
    print *, ieee_value(1.0_wp, ieee_negative_inf)
end program ieee

This might be handy to have in a future release to deal better with coding infinity into mathematical functions. For infinity I just set a very large number as a break point.

Lester

Lester

Thank you for the feedback. I have made a note of your suggestion.

This is a part of the 2003 Standard that has not yet been implemented in FTN95.

At the moment computing z = 0.0 then v = 1.0/z will raise a runtime time exception as will v = z/z. This default exception handling will need to be changed when implementing the ieee_arithmetic module and this could be unsafe if the programmer is not fully aware if the implications.

The next release of FTN95 and its associated DLLs will provide support for the Fortran 2003 intrinsic IEEE_ARITHMETIC module. This is particularly for x64, with some support for Win32.

A new routine TRAP_FP_EXCEPTIONS@ will be released for x64 but not for Win32.

SUBROUTINE TRAP_FP_EXCEPTIONS@(trap) INTEGER trap A trap value of zero masks all floating point runtime exceptions. A non-zero value restores the default state where floating point exceptions lead to a runtime failure.

This routine is not provided for Win32 because the the existing TRAP_EXCEPTION@ function does not enable progression (i.e. the CONTINUE_EXECUTION return state) after handling a floating point exception.

1. TRAP_FP_EXCEPTIONS@ is implemented independently of the IEEE_ARITHMETIC module.
2. Standard PRINT and WRITE statements will display 'NaN', 'Infinity', or '-Infinity' where appropiate (depending on the field width) and this is independent of IEEE_ARITHMETIC. The current output is '????....'.
3. Users who want to mask floating point exceptions must use x64 and must call TRAP_FP_EXCEPTIONS@(0) for related sections of their code.

Example

real t,z,v(6) z = 0.0 t = tiny(z) call trap_fp_exceptions@(0) v = [z/z,z/1.0,-z/1.0,1.0/z,-1.0/z,t/10] call trap_fp_exceptions@(1) do i = 1,6; print*, v(i); end do end

Output:

NaN 0.00000 0.00000 Infinity -Infinity 0.00000

The new IEE_ARITHMETIC module now gives support from +/- infinity (as of ftn85 v9.05)

program ieee use, intrinsic :: iso_fortran_env, only: wp=>real64 use, intrinsic :: ieee_arithmetic implicit none

print *, ieee_value(1.0_wp, ieee_positive_inf)
print *, ieee_value(1.0_wp, ieee_negative_inf)

end program ieee

Output:

Infinity -Infinity

Lester