set_ieee_rounding_mode(3I)

NAME
     SET_IEEE_ROUNDING_MODE - Alters current floating-point rounding mode
     state and restores the floating-point rounding mode before exiting a
     procedure

SYNOPSIS
     SET_IEEE_ROUNDING_MODE ([ROUNDING_MODE=]rounding_mode)

STANDARDS
     Fortran extension

     IEEE Standard for Binary Floating-point Arithmetic

DESCRIPTION
     The SET_IEEE_ROUNDING_MODE intrinsic subroutine is typically used to
     alter the current floating-point rounding mode state and to restore
     the caller's floating-point rounding mode just before exiting a
     procedure.  It accepts the following argument:

     rounding_mode
               Must be scalar and of an integer type that occupies a full
               word.  It is an INTENT(IN) argument.

               The floating-point rounding mode is set to the rounding mode
               indicated by rounding_mode.

               rounding_mode must have one of the values represented by the
               following named constants:

               * IEEE_RM_NEAREST

               * IEEE_RM_POS_INFINITY

               * IEEE_RM_ZERO

               * IEEE_RM_NEG_INFINITY

               rounding_mode is assumed to have been set through an
               invocation of GET_IEEE_ROUNDING_MODE(3I).

     The IEEE_REAL(3I) and IEEE_INT(3I) functions are the only routines
     supplied by SGI that examine the setting of the rounding mode on IRIX
     systems.

     The name of this intrinsic cannot be passed as an argument.

NOTES
     The IEEE intrinsic procedures use the named constants contained in a
     system module, so you must include the following statement in your
     program:

          USE FTN_IEEE_DEFINITIONS

EXAMPLES
        ! Assume the following code is executing on a machine where default
        ! integer occupies a full word.

        INTEGER  save_rounding_mode

        ! Save the current rounding mode then change the rounding mode
        ! to round to positive infinity.

        CALL GET_IEEE_ROUNDING_MODE(save_rounding_mode)
        CALL SET_IEEE_ROUNDING_MODE(IEEE_RM_POS_INFINITY)

        ! Calculate the upper bound on sum.

        DO i = 1, n
           xup(i)  = y(i) + z(i)
        END DO

        ! Reset to round to negative infinity mode.

        CALL SET_IEEE_ROUNDING_MODE(IEEE_RM_NEG_INFINITY)

        ! Calculate lower bound on sum.

        DO i = 1, n
           xdn(i) = y(i) + z(i)
        END DO

        ! Restore original rounding mode and return to the caller.

        CALL SET_IEEE_ROUNDING_MODE(save_rounding_mode)

SEE ALSO
     GET_IEEE_ROUNDING_MODE(3I)