02-19-2010, 10:15 PM
britlion Wrote:I was too, especially given the little tutorial I wrote about using smaller data types when possible to get the fastest code - we know handling five byte numbers (and in the rom routines too) is slower than integers.
You can see the code I wrote and ran - it finds sin(2), ln(2) and 2^2 in the loop. I'm pretty sure the 2^2 uses integer math, and rightly so; but sin and ln...well... if you're using ROM routines, I have no idea why it came back that fast. Does it work out a fixed result for sin(2) and just use that? That would be one reason it works so quickly!
It ISN'T printing the numbers, because it would make it very slow - PRINT is a pretty time consuming thing to do. I'm wondering if it might be possible to have a faster print routine that doesn't do all the bounds checking, and control character checking. I tested the loop with printing on - and it spun through some decimals happily. I timed it with printing off. I did wonder if the compiler would optimize out data that wasn't being used. The time results for this test were staggeringly fast.
Ok, that's the explanation: precalculation and constant folding => 2^2 => 4, and so on. All those values are constant, and they're calculated at compile time. Even more, if O3 were in use, this program could be reduced to a single NOP, as it does nothing (it does not print on the screen). :!:
Try declaring a Float a = 2 variable, and use Sin(a), Ln(a), 2^a, etc... It should have a speed similar to the ROM-BASIC FP calc (so slow).