Simon,
Thanks for the explanation!
In Java int is 32 bit as well.
I have just replaced ints with longs in Java and found out that now I get
the Java speed also very similar to Julia.
However I tried in Cython:
def primes_list(int kmax):
cdef int k, i
cdef long n
cdef long p[20000]
...
and surprisingly the speed did not change...at first I thought that maybe
something did not compile or is in cache - but I made sure - it's not the
cache.
Cython speed remains unchanged regardles using int or long?
I know that now it becomes other language question...but maybe someone can
explain?
All best,
Przemyslaw Szufel
On Tuesday, 14 January 2014 23:29:40 UTC+1, Simon Kornblith wrote:
>
> With a 64-bit build, Julia integers are 64-bit unless otherwise specified.
> In C, you use ints, which are 32-bit. Changing them to long long makes the
> C code perform similarly to the Julia code on my system. Unfortunately,
> it's hard to operate on 32-bit integers in Julia, since + promotes to
> 64-bit by default (am I missing something)?
>
> Simon
>
> On Tuesday, January 14, 2014 4:32:16 PM UTC-5, Przemyslaw Szufel wrote:
>>
>> Dear Julia users,
>>
>> I am considering using Julia for computational projects.
>> As a first to get a feeling of the new language a I tried to benchmark
>> Julia speed against other popular languages.
>> I used an example code from the Cython tutorial:
>> http://docs.cython.org/src/tutorial/cython_tutorial.html [ the code for
>> finding n first prime numbers].
>>
>> Rewriting the code in different languages and measuring the times on my
>> Windows laptop gave me the following results:
>>
>> Language | Time in seconds (less=better)
>>
>> Python: 65.5
>> Cython (with MinGW): 0.82
>> Java : 0.64
>> Java (with -server option) : 0.64
>> C (with MinGW): 0.64
>> Julia (0.2): 2.1
>> Julia (0.3 nightly build): 2.1
>>
>> All the codes for my experiments are attached to this post (Cython i
>> Python are both being run starting from the prim.py file)
>>
>> The thing that worries me is that Julia takes much much longer than
>> Cython ,,,
>> I am a beginner to Julia and would like to kindly ask what am I doing
>> wrong with my code.
>> I start Julia console and use the command include ("prime.jl") to
>> execute it.
>>
>> This code looks very simple and I think the compiler should be able to
>> optimise it to at least the speed of Cython?
>> Maybe I my code has been written in non-Julia style way and the compiler
>> has problems with it?
>>
>> I will be grateful for any answers or comments.
>>
>> Best regards,
>> Przemyslaw Szufel
>>
>
