Sorry for the wrong info, I was switching between a 32 bit and a 64 bit machine (SSH terminal), and I just happened to run the script on the 32 bit machine...
On Wednesday, January 15, 2014 12:37:07 AM UTC+1, Przemyslaw Szufel wrote: > > Foldes, > > I went for your solution and got a time increase from > 2.1 seconds (64bit integers) to 17.78 seconds (32 bit dow-casting). > Seems like casting is no cheap... > > Any other ideas possibilities? > > All best, > Przemyslaw > > P.S. > Naturally I realize that this is toy example and normally in a typical > production code we would rather use real numbers for computations not ints. > I am asking just out of curiosity ;-) > > > On Wednesday, 15 January 2014 00:25:20 UTC+1, Földes László wrote: >> >> You can force the literals by enclosing them in int32(): >> >> p = [int32(0) for i=1:20000] >> result = [int32(0) for i=1:20000] >> k = int32(0) >> n = int32(2) >> while k < int32(20000) >> i = int32(0) >> >> >> >> On Wednesday, January 15, 2014 12:04:23 AM UTC+1, Przemyslaw Szufel wrote: >>> >>> Simon, >>> Thanks! >>> I changed in Cython to >>> def primes_list(int kmax): >>> cdef int k, i >>> cdef long long n >>> cdef long long p[20000] >>> and now I am getting 2.1 seconds - exactly the same time as Julia and >>> Java with longs... >>> >>> Since the computational difference between 64bit longs and 32bit ints is >>> soo high - is there any way to rewrite my toy example to force Julia to do >>> 32 bit int calculations? >>> >>> All best, >>> Przemyslaw Szufel >>> >>> >>> On Tuesday, 14 January 2014 23:55:12 UTC+1, Simon Kornblith wrote: >>>> >>>> In C long is only guaranteed to be at least 32 bits (IIRC it's 64 bits >>>> on 64-bit *nix but 32-bit on 64-bit Windows). long long is guaranteed >>>> to be at least 64 bits (and is 64 bits on all systems I know of). >>>> >>>> Simon >>>> >>>> On Tuesday, January 14, 2014 5:46:04 PM UTC-5, Przemyslaw Szufel wrote: >>>>> >>>>> 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 >>>>>>> >>>>>>
