Re: C is it faster than numpy

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Hi,
What do you mean?
the python and C programs are not equivalent?


Le ven. 25 f=C3=A9vr. 2022 =C3=A0 10:42, Giorgio Zoppi <giorgio.zoppi@gmail=
.com> a
=C3=A9crit :

> Well,
> numpy is written in C :) Maybe your C is not the numpy equivalent?
> Best Regards,
> Giorgio
>
> Il giorno ven 25 feb 2022 alle ore 09:03 BELAHCENE Abdelkader <
> [email protected]> ha scritto:
>
>> Hi,
>> a lot of people think that C (or C++) is faster than python, yes I agree=
,
>> but I think that's not the case with numpy, I believe numpy is faster th=
an
>> C, at least in some cases.
>>
>>
>> *Is there another explanation ?Or where can find  a doc speaking  about
>> the subject?*Thanks a lot
>> Regards
>> Numpy implements vectorization for arrays, or I'm wrong. Anyway here is
>> an example Let's look at the following case:
>> Here is the result on my laptop i3:
>>
>> Labs$ *python3 tempsExe.py  50000*
>>   sum with Python: 1250025000 and NumPy 1250025000
>>       time used Python Sum: * 37.28 sec *
>>       time used  Numpy Sum:  *1.85 sec*
>>
>> Labs$ *./tt    50000 *
>>
>>
>> *   CPU  time :7.521730    The value : 1250025000 *
>> --------------------------------------------
>>
>> This is the Python3 program :
>>
>> import timeit as it
>> import numpy as np
>> import sys
>> try :
>> n=3Deval(sys.argv[1])
>> except:
>> print ("needs integer as argument") ; exit()
>>
>> a=3Drange(1,n+1)
>> b=3Dnp.array(a)
>> def func1():     return sum(a)
>> def func2(): return np.sum(b)
>>
>> print(f"sum with Python: {func1()} and NumPy {func2()} ")
>> tm1=3Dit.timeit(stmt=3Dfunc1, number=3Dn)
>> print(f"time used Python Sum: {round(tm1,2)} sec")
>> tm2=3Dit.timeit(stmt=3Dfunc2, number=3Dn)
>> print(f"time used  Numpy Sum: {round(tm2,2)} sec")
>>
>> and Here the C program:
>> #include <time.h>
>> #include <stdio.h>
>> #include <stdlib.h>
>> long func1(int n){
>>          long  r=3D0;
>>         for (int  i=3D1; i<=3D n;i++) r+=3D i;
>>          return r;
>> }
>> int main(int argc, char* argv[]){
>>          clock_t c0, c1;
>>         long v,count; int n;
>>        if ( argc < 2) {
>>               printf("Please give an argument");
>>              return -1;
>>       }
>>     n=3Datoi(argv[1]);
>>     c0 =3D clock();
>>      *for (int j=3D0;j < n;j++) v=3Dfunc1(n);*
>>      c1 =3D clock();
>>      printf ("\tCPU  time :%.2f sec", (float)(c1 - c0)/CLOCKS_PER_SEC);
>>      printf("\n\tThe value : %ld\n",  v);
>> }
>> _______________________________________________
>> python-uk mailing list
>> [email protected]
>> https://mail.python.org/mailman/listinfo/python-uk
>>
>
>
> --
> Life is a chess game - Anonymous.
> _______________________________________________
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<div dir=3D"ltr"><div>Hi,</div><div>What do you mean?</div><div>the python =
and C programs are not equivalent?</div><div><br></div></div><br><div class=
=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail_attr">Le=C2=A0ven. 25 f=C3=
=A9vr. 2022 =C3=A0=C2=A010:42, Giorgio Zoppi &lt;<a href=3D"mailto:giorgio.=
[email protected]">[email protected]</a>&gt; a =C3=A9crit=C2=A0:<br></d=
iv><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;bord=
er-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir=3D"ltr">Well,=
<div>numpy is written in C :) Maybe your C is not the numpy equivalent?</di=
v><div>Best Regards,</div><div>Giorgio</div></div><br><div class=3D"gmail_q=
uote"><div dir=3D"ltr" class=3D"gmail_attr">Il giorno ven 25 feb 2022 alle =
ore 09:03 BELAHCENE Abdelkader &lt;<a href=3D"mailto:abdelkader.belahcene@e=
nst.dz" target=3D"_blank">[email protected]</a>&gt; ha scritto:<=
br></div><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8e=
x;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir=3D"ltr"=
>Hi,<br>a lot of people think that C (or C++) is faster than python, yes I =
agree, but I think that&#39;s not the case with numpy, I believe numpy is f=
aster than C, at least in some cases.<br><b>Is there another explanation ?<=
br>Or where can find =C2=A0a doc speaking =C2=A0about the subject?<br></b>T=
hanks a lot <br>Regards<br>Numpy implements vectorization for arrays, or I&=
#39;m wrong. Anyway here is an example Let&#39;s look at the following case=
:<br>Here is the result on my laptop i3:<br><br>Labs$ <b>python3 tempsExe.p=
y=C2=A0 50000</b> <br>=C2=A0 sum with Python: 1250025000 and NumPy 12500250=
00<br>=C2=A0 =C2=A0 =C2=A0 time used Python Sum:=C2=A0<b> 37.28 sec </b><br=
>=C2=A0 =C2=A0 =C2=A0 time used =C2=A0Numpy Sum:=C2=A0 <b>1.85 sec</b><br><=
br>Labs$ <b>./tt =C2=A0=C2=A0 50000 	</b><br>=C2=A0<b> =C2=A0 CPU =C2=A0tim=
e :7.521730<br>=C2=A0 =C2=A0 The value : 1250025000 <br></b>---------------=
-----------------------------<br><br>This is the Python3 program :<br><br>i=
mport timeit as it<br>import numpy as np<br>import sys<br>try :<br>	n=3Deva=
l(sys.argv[1])<br>except:<br>	print (&quot;needs integer as argument&quot;)=
 ; exit()<br>	<br>a=3Drange(1,n+1)<br>b=3Dnp.array(a)<br>def func1(): =C2=
=A0 =C2=A0 return sum(a)<br>def func2():	 return np.sum(b)<br><br>print(f&q=
uot;sum with Python: {func1()} and NumPy {func2()} &quot;)<br>tm1=3Dit.time=
it(stmt=3Dfunc1, number=3Dn)<br>print(f&quot;time used Python Sum: {round(t=
m1,2)} sec&quot;)<br>tm2=3Dit.timeit(stmt=3Dfunc2, number=3Dn)<br>print(f&q=
uot;time used =C2=A0Numpy Sum: {round(tm2,2)} sec&quot;)<br><br>and Here th=
e C program:<br>#include &lt;time.h&gt;<br>#include &lt;stdio.h&gt;<br>#inc=
lude &lt;stdlib.h&gt;<br>long func1(int n){<br>=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0 long =C2=A0r=3D0;<br>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0 for (int =C2=A0i=3D1; i&lt;=3D n;i++) r+=3D i;<br>=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 return r;<br>}<br>int main(int argc, c=
har* argv[]){<br>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 clock_t c=
0, c1; <br>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 long v,count; int n;<=
br>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if ( argc &lt; 2) {<br>=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 printf(&=
quot;Please give an argument&quot;);<br>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 return -1;<br>=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0 }<br>=C2=A0=C2=A0=C2=A0 n=3Datoi(argv[1]); <br>=C2=A0=C2=A0=C2=A0=
 c0 =3D clock();<br>=C2=A0=C2=A0=C2=A0=C2=A0 <b>for (int j=3D0;j &lt; n;j++=
)	v=3Dfunc1(n);</b><br>=C2=A0=C2=A0=C2=A0=C2=A0 c1 =3D clock();<br>=C2=A0=
=C2=A0=C2=A0=C2=A0 printf (&quot;\tCPU =C2=A0time :%.2f sec&quot;, (float)(=
c1 - c0)/CLOCKS_PER_SEC);<br>=C2=A0=C2=A0=C2=A0=C2=A0 printf(&quot;\n\tThe =
value : %ld\n&quot;, =C2=A0v);<br>}<br></div>
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</blockquote></div><br clear=3D"all"><div><br></div>-- <br><div dir=3D"ltr"=
><div dir=3D"ltr">Life is a chess game - Anonymous.<br></div></div>
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python-uk mailing list<br>
<a href=3D"mailto:[email protected]" target=3D"_blank">python-uk@python.=
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errer" target=3D"_blank">https://mail.python.org/mailman/listinfo/python-uk=
</a><br>
</blockquote></div>

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