Re: What is faster Ada or C?

[Jacob Sparre Andersen <sparre@nbi.dk>]

Robert Dewar wrote:

> Jacob Sparre Andersen <sparre@nbi.dk> wrote in message news:<3C10F77E.6BDD9A3B@nbi.dk>...
> > When I look at the corresponding assembler code (gnatgcc
> > -S/g++ -S) I can see that GNU C++ inlines the square root
> > function, while GNU Ada doesn't.
> 
> You seem to be assuming that the function called square root in C++
> and the function called square root in Ada
> are the same function,

Correct.

> presumably because their names
> are similar, and both are usable in your context, but they
> are not at all the same routine. The Ada routine has additional
> semantics not present in the C++ routine (e.g.
> the handling of -0.0 which is required to return -0.0).

I had forgotten (or had not noticed) this.

> Those extra tests take significant time. Now one can sit
> back and say "Ada is a junk language, it insists on testing
> for errors at runtime, and in giving accurate IEEE results,
> and I don't need either",

I happen to need accurate results, and I appreciate being
able to specify things like the number of significant digits
in my floating point types. But I am (as a physicist) not
used to -0.0 being different from +0.0, nor to being unable
to calculate the square root of -0.0, as your explanations
seem to indicate that IEEE floating point processors are.

> but that's not a very reasonable
> position given that if you like you can easily call the
> C routine directly, since Ada, unlike other languages,
> carefully defines the syntax and semantics of calling routines written
> in other languages :-)

Since I - in the example program - know that the values will
never get close to zero, I suppose that I can use the C
function "sqrt".

Jacob
-- 
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