Subject:
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Re: floating point operation
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Newsgroups:
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lugnet.robotics.rcx.legos
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Date:
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Wed, 28 Nov 2001 20:38:44 GMT
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Viewed:
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1497 times
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Dennis Diehl <dennis@mathematik.uni-freiburg.de> wrote:
> What is the reason for this difference?
Compiler optimization? At least, a disassembly of similar code showed me
that that seemed to be the case.
The compiler can see that t is not used. Try returning t, or copying t to
a global before you return from main. That will make things closer I
think, but of course the first version will still run faster in the end.
-Kekoa
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Message has 1 Reply:
 | | Re: floating point operation
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| (...) I should clarify that this is true for the first version only. For some reason, the compiler does not optimize the second version in the same way. Anyways, what I see in the disassembly for the first version is a loop to 100 inside a loop to (...) (23 years ago, 28-Nov-01, to lugnet.robotics.rcx.legos)
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Message is in Reply To:
| | floating point operation
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| I did some experiments with floating point operations and I was surprised when I tried this: int main(){ long t1; int i,j; float t; t1 = sys_time; for(j=0; j<1000; j++){ t=0.06; for(i=0; i<100; i++){ t=1.7*t; } } lcd_int((sys_time - t1)/1000); (...) (23 years ago, 28-Nov-01, to lugnet.robotics.rcx.legos)
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