[fpc-devel] Extended type

[Florian Klämpfl]

Am 20.04.2011 00:05, schrieb Hans-Peter Diettrich:
> Florian Klaempfl schrieb:
> 
>> Using extended typically hides only bad numerical algorithms. There
>> might be some corner cases where extended is usefull but I general I
>> think it's a matter of bad algorithms.
> 
> Some algorithms convert faster with increased accuracy.

I guess you meant converge? This might be true, but processing of
extended types is also slower: the memory footprint increases and even
worse, extended arrays are typically aligned to 4 or even 16 byte
borders so they take 12 or 16 byte in memory. Further, more complex
floating point operations than +,-,* are also typically slower when the
fpu is set to extended precision. So even if an algorithm converges in
less steps with extended, the overall computation time might not decrease.