GCC beaten by ICC in stupid trig test!

[Toon Moene]

I wrote:

> Dave Korn wrote:
> 
>  >   IIUIC the fact that the + operator is specified in the standard as
>  > binding left-to-right imply that "a + b + c" with no brackets *has* to
>  > be interpreted as "(a + b) + c".
> 
> No, it establishes the way the multi-operator expressions may be 
> combined *for interpretation*.  I.e., what the expression means (on a 
> high level, before applying such rules as 1.4 (6) [This standard does 
> not specify] ... the method of rounding, approximating or computing 
> numeric values on a particular processor").

This might not be as clear as possible, because '+' happens to be 
associative in the REAL world.

What the Fortran standard wants to make clear is that a grouping is 
necessary to establish an interpretation for unparenthesized expressions 
with more than one operator.

The example with '+' is trivial, because '+' is associative in the real 
numbers, so a standard-enforced ordering is superfluous.

However, this is not true of '/' (division) or '**' (exponentiation). 
Therefore, the standard establishes that for division:

A / B / C   means   (A / B) / C   and not   A / (B / C)

and for exponentiation:

A ** B ** C   means   A ** (B ** C)   and not   (A ** B) ** C

Both interpretations follow mathematical practice, but still have to be 
defined for the standard.

Hope this helps,

-- 
Toon Moene - mailto:toon@moene.indiv.nluug.nl - phoneto: +31 346 214290
Saturnushof 14, 3738 XG  Maartensdijk, The Netherlands
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GNU Fortran 95: http://gcc.gnu.org/fortran/ (under construction)