No subject

[Fred Tydeman]

Subject:  Exceptions:  ANSI C vs IEEE-754
 
There appears to be a direct conflict  between ANSI C and IEEE-754 for
what should happen on exceptions.  For example, y = sqrt(-1.0);
 
ANSI C says the each function (in  math.h) shall execute as if it were
a single operation, with generating  any externally visible exceptions
(ANSI  C,  February  14,  1990,   section  4.5.1  Treatment  of  Error
Conditions).
 
IEEE-754  says that  sqrt(-1.0)  shall  signal the  invalid  operation
exception (IEEE Std 754-1985, section 7.1 Invalid Operation).
 
In a  trapping environment, this appears  to be a direct  conflict, as
IEEE says to take  a trap to a user trap handler,  whereas ANSI C says
that  the user  cannot see  this exception  and that  the user's  trap
handler cannot be called.
 
How is NCEG going to resolve this conflict?