Re: Basics on real floating types


"Eric Sosman" <esosman@xxxxxxxxxxxxxxxxxxxx> wrote in message news:hdej4u$93t$1@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
bartc wrote:

"Eric Sosman" <esosman@xxxxxxxxxxxxxxxxxxxx> wrote in message news:hdedcg$q07$1@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Dann Corbit wrote:
[...]
With memory at low, low prices it seem hard to come up with sensible reasons to prefer float over double for the vast majority of applications. [...]

One significant influence can be speed. Memory may be

What happened to your disdain for the little tin god?

What happened to your ability to discriminate between
a (potential) twofold speedup and the overhead of one trivial
function call? Size matters.

There's nothing wrong with it. I've just tested the overhead of adding one extra level of function call to a (admittedly fairly trivial) function. It was something like 50% (and up to 100% on one test). That's not far off the figures you're talking about.

Now an application probably won't spend all it's time calling that wrapper function, but then it might not spend all it's time calculating with floats either.

And of course that extra wrapper code will also require space in the instruction cache. If function call overhead didn't matter than no compiler would ever bother with inlining.

--
Bartc

.

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