(Yes, I konw whats an object is...)
BTW. I did a translation of a pi callculation programm in C to Python.
(Do it by your own... ;-)
--------
Calc PI for 800 digs(?). (german: Stellen)
------
int a=10000,b,c=280 0,d,e,f[2801],g;main(){for(; b-c;)f[b++]=a/5;
for(;d=0,g=c*2; c-=14,printf("%.4 d",e+d/a),e=d%a)for(b= c;d+=f[b]*a,
f[b]=d%--g,d/=g--,--b;d*=b);}
$ ./a.exe
314159265358979 323846264338327 950288419716939 937510582097494 459230781640628 62089
986280348253421 170679821480865 132823066470938 446095505822317 253594081284811 17450
284102701938521 105559644622948 954930381964428 810975665933446 128475648233786 78316
527120190914564 856692346034861 045432664821339 360726024914127 372458700660631 55881
748815209209628 292540917153643 678925903600113 305305488204665 213841469519415 11609
433057270365759 591953092186117 381932611793105 118548074462379 962749567351885 75272
489122793818301 194912983367336 244065664308602 139494639522473 719070217986094 37027
705392171762931 767523846748184 676694051320005 681271452635608 277857713427577 89609
173637178721468 440901224953430 146549585371050 792279689258923 542019956112129 02196
086403441815981 362977477130996 051870721134999 999837297804995 105973173281609 63185
--------
But Python is much slower here then C here. I used a while-loop within a
while-loop. Not that much calculation here.
21  2601 
mm wrote:
(Yes, I konw whats an object is...)
BTW. I did a translation of a pi callculation programm in C to Python.
(Do it by your own... ;-)
Is that a question on how to optimize code you won't show us? If yes, I'm
sorry to tell you that crystal balls are short these days. Too much
new-year-outlooks.
Diez
Hmm... it's a question. It was not that easy to translate this #@*?%!
C-Program into readable code and then to Python. But it works.
There are only two while-loops (a while within an other while).
I konw, that for example while-loops in Perl are very slow. Maybe this
is also known in Pyhton. Then, I can translate the while-loops in to
for-loops, for example.
More general, maybe there is a speed optimazation docu out there.
(Anyway, this code for C-calc is complex. And I realy don't understand
it right now... 8-)
But anyway, there is not that much calculation, it has more something to
do with the too while-loops. Here is some code:
(In general, it has basically nothing to do with PI-calc.)
c=2800 ## a counter
while c*2:
## do some calc. did not change c here.
...
b=c ## number of elements
while (b-1):
## so some calc.
...
b=b-1 ## just for while-loop condition.
c = c-14; ## this is code vor the 1st while-loop, BUT bust run after
the 2nd-while-loop.
pi = pi + str("%04d" % int(e + d/a)) ## this should be fast?! I dont
know.
There are a output string, a list, and integers. No complex data
structures; and no complex calculations.
Diez B. Roggisch wrote:
mm wrote:
>>(Yes, I konw whats an object is...)
BTW. I did a translation of a pi callculation programm in C to Python.
(Do it by your own... ;-)
Is that a question on how to optimize code you won't show us? If yes, I'm
sorry to tell you that crystal balls are short these days. Too much
new-year-outlooks.
Diez
Ah, no. It was a HASH (assoziative Array or somethings like that).
mm wrote:
>
I konw, that for example while-loops in Perl are very slow. Maybe this
is also known in Pyhton. Then, I can translate the while-loops in to
for-loops, for example.
More general, maybe there is a speed optimazation docu out there.
Using the '+' operator for string concatonation can be slow, especially
when done many times in a loop.
pi = pi + str("%04d" % int(e + d/a)) ## this should be fast?! I dont
The accepted solution would be to make pi an array and append to the
end...
pi = [] #create the array (empty)
....
....
pi.append(str(" %04d"%int(e+d/a))) # append to it
And when it is time to print the results do the following:
print "".join(pi)
It may look strange, but it is a common Python idiom. You might also
look into an optimizer such as psycho: http://psyco.sourceforge.net/.
On 2007-01-03 16:50, mm wrote:
More general, maybe there is a speed optimazation docu out there.
At least Alex Martellis "Python in a Nutshell" has a section on
optimization.
I presented this at the last EuroPython conference: http://sschwarzer.com/download/optim...python2006.pdf
Stefan
--
Dr.-Ing. Stefan Schwarzer
SSchwarzer.com - Softwareentwick lung für Technik und Wissenschaft http://sschwarzer.com
Hmm.. thanks. I did this changes, but without any performance profits.
Matimus wrote:
Using the '+' operator for string concatonation can be slow, especially
when done many times in a loop.
> pi = pi + str("%04d" % int(e + d/a)) ## this should be fast?! I dont
The accepted solution would be to make pi an array and append to the
end...
pi = [] #create the array (empty)
...
...
pi.append(str(" %04d"%int(e+d/a))) # append to it
And when it is time to print the results do the following:
print "".join(pi)
It may look strange, but it is a common Python idiom. You might also
look into an optimizer such as psycho: http://psyco.sourceforge.net/.
Yes. But it still runns very slowly.
If someone is really interested in speed optimization, I can publish my
PI-calc code.
Maybe for some Python compiler/interpreter hackers... ;-)
(There are only 2 while-loops, one within another, and some simple basic
calculations. Nothing special.)
Stefan Schwarzer wrote:
On 2007-01-03 16:50, mm wrote:
>>More general, maybe there is a speed optimazation docu out there.
At least Alex Martellis "Python in a Nutshell" has a section on
optimization.
I presented this at the last EuroPython conference:
http://sschwarzer.com/download/optim...python2006.pdf
Stefan
At Wednesday 3/1/2007 12:50, mm wrote:
>Hmm... it's a question. It was not that easy to translate this #@*?%!
C-Program into readable code and then to Python. But it works.
Because that code was written with C in mind, and uses some C
subtlecies (uhm, got it right?) obscuring the original algorithm.
BTW, do you know where the algorithm was taken from?
>while c*2:
`while c:` does *exactly* the same without computing (and discarding)
an intermediate object.
while (b-1):
If b>=1 initially (as it should, else this will be a loooooong loop),
this is the same as `while b>1:` but without computing (and
discarding) an intermediate object.
b=b-1 ## just for while-loop condition.
I'm not sure if the compiler is smart enough to translate this into `b -= 1`
c = c-14; ## this is code vor the 1st while-loop, BUT bust run after
Same as above
pi = pi + str("%04d" % int(e + d/a)) ## this should be fast?! I dont
Someone else already pointed out how to improve this.
You don't show the rest of the code...
--
Gabriel Genellina
Softlab SRL
_______________ _______________ _______________ _____
Preguntá. Respondé. Descubrí.
Todo lo que querías saber, y lo que ni imaginabas,
está en Yahoo! Respuestas (Beta).
¡Probalo ya! http://www.yahoo.com.ar/respuestas
If someone is really interested in speed optimization, I can publish my
PI-calc code.
I wouldn't mind seeing it. Chances are you will get much better help if
you post your code anyway.
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