4.3BSD-UWisc/man/cat3/trapov.3f

TRAPOV(3F)          UNIX Programmer's Manual           TRAPOV(3F)



NAME
     trapov - trap and repair floating point overflow

SYNOPSIS
     subroutine trapov (numesg, rtnval)
     double precision rtnval

DESCRIPTION
     NOTE: This routine applies only to the older VAX 11/780's.
     VAX computers made or upgraded since spring 1983 handle
     errors differently.  See _t_r_p_f_p_e(3F) for the newer error
     handler.  This routine has always been ineffective on the
     VAX 11/750.  It is a null routine on the PDP11.

     This call sets up signal handlers to trap arithmetic excep-
     tions and the use of illegal operands.  Trapping arithmetic
     exceptions allows the user's program to proceed from
     instances of floating point overflow or divide by zero.  The
     result of such operations will be an illegal floating point
     value.  The subsequent use of the illegal operand will be
     trapped and the operand replaced by the specified value.

     The first _n_u_m_e_s_g occurrences of a floating point arithmetic
     error will cause a message to be written to the standard
     error file.  If the resulting value is used, the value given
     for _r_t_n_v_a_l will replace the illegal operand generated by the
     arithmetic error.  _R_t_n_v_a_l must be a double precision value.
     For example, ``0d0'' or ``dflmax()''.

FILES
     /usr/lib/libF77.a

SEE ALSO
     trpfpe(3F), signal(3F), range(3F)

BUGS
     Other arithmetic exceptions can be trapped but not repaired.

     There is no way to distinguish between an integer value of
     32768 and the illegal floating point form.  Therefore such
     an integer value may get replaced while repairing the use of
     an illegal operand.













Printed 12/27/86          May 15, 1985                          1