On 26/03/2018 00:27, Richard Damon wrote:
On 3/25/18 8:32 AM, bartc wrote:
Using CPython on my machine, doing a string to int conversion that
specific number took 200 times as long as doing a normal assignment.
That conversion took 4 microseconds.
Not significant if it's only done once. But it might be executed a
million times.
The other half of that thought is how does the 4 microseconds to create
the constant compare to the operations USING that number. My guess is
that for most things the usage will swamp the initialization, even if
that is somewhat inefficient.
Calling a function that sets up C using 'C = 288714...' on one line, and
that then calculates D=C+C, takes 0.12 seconds to call 1000000 times.
To do D=C*C, takes 2.2 seconds (I've subtracted the function call
overhead of 0.25 seconds; there might not be any function call).
If I instead initialise C using 'C = int("288712...")', then timings
increase as follows:
0.12 => 3.7 seconds
2.2 => 5.9 seconds
So the overhead /can/ be substantial, and /can/ be significant compared
with doing bignum calculations.
Of course, once initialised, C might be used a hundred times, then the
overhead is less significant. But it is not small enough to just dismiss.
--
bartc
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