Services & ResourcesWolfram ForumsMathGroup Archive

[Date Index] [Thread Index] [Author Index]

Re: style question

• To: mathgroup at smc.vnet.net
• Subject: [mg79485] Re: style question
• From: Peter Pein <petsie at dordos.net>
• Date: Fri, 27 Jul 2007 06:05:14 -0400 (EDT)
• References: <200707241008.GAA26147@smc.vnet.net> <f89rdm$6d1$1@smc.vnet.net>

Carl Woll schrieb:

> For this particular problem (in version 6), it's faster to use 
> arithmetic and total:
> 
> In[1]:= k = 10^6;
> m1 = RandomInteger[1, {k, 2, 2}];
> m2 = RandomInteger[1, {k, 2, 2}];
> 
> In[4]:= Timing[
>  matches = Thread[temporary[m1, m2]] /. temporary -> Equal;
>  Count[matches, True]]
> 
> Out[4]= {3.453, 62300}
> 
> In[5]:= Count[Total[Unitize[m1 - m2], {2, 3}], 0] // Timing
> 
> Out[5]= {0.391, 62300}
> 
> Carl Woll
> Wolfram Research
> 

Hello Carl,

doesn't Unitize[x]==0 imply x==0? And when only zeroes are counted, why
the call to Unitize?

I can not try to explore the difference (if any) because version 5.2
does not allow Total with a range of levelspecs.

Peter

• Follow-Ups:
  • Re: Re: style question
    • From: Carl Woll <carlw@wolfram.com>

• References:
  • style question
    • From: Yaroslav Bulatov <yaroslavvb@gmail.com>