Re: Do I really have to use an array?

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Thu, 24 Jan 2008 18:55:17 GMT
On 2008-01-24 13:41, Daniel T. wrote:

mike3 <> wrote:

I can't believe I may have to use an array here.

I've got this bignum package I was making in C++ for a fractal
generator, and tried an approach that was suggested to me here a while
back, about using a "stack of vectors" instead of a static array.

Anyway, I put the suggestion into effect, and it seems the routine
that uses the stack of vectors (an in-place multiplication routine) is
real slow -- too slow for my liking. The out-of-place multiplication
is like twice as fast. What gives? Do I really have to use an evil
array on the stack? (in my code it would be something like "Digit
tmpBuf[2*MAX_PRECISION]".) I don't think so since it was said the
stack-of-vectors approach can be at least as fast as the array.

You can get the relevant code snippets here if you need to see them:

Did you turn on optimization? In some systems vector does a whole bunch
of error checking unless full optimizations have been turned on.

OT: In Visual Studio I think you have to do a bit more than just turn on
optimisations, look in the documentation for checked iterators.

Erik Wikstr?m

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