/var/log/mind - Latest Comments

Re: 2009 is not a prime number. A python program to compute factors.

Jaime — Thu, 26 Feb 2009 09:16:44 -0000

I hope you people realize how inefficient the code you've written is... After you've divided out all the 2's from the number, you still try to find out if it is divisible by 4,6,8,10,12... If nothing else, you should only do trial division by odd numbers. Or even better, if you can afford the memory cost, generate first a list of all prime numbers below sqrt(n), and then do trial division by those only...

Re: Java : the perpetually undead language

Ignaci — Tue, 06 Jan 2009 03:02:54 -0000

Boss!! and Bossess!!!! Please use perl for everything. Perl is ultimate for any purpose. Python is slow (even with psycho, pypy) and Java is over verbose. (But Java is faster)

Check modperl before u make a comment about enterprise software. Most companies I am dealing with use modperl for enterprise applications. Perl is unbeatable.

Also, WxPerl takes off recently. Till recently, I was waiting for a Tk plugin in browsers to embed graphic applications in a server page for perl (just like swing application put in JSP using plugin). But, DOJO, AJAX stumped me and made me feel -----> "No need of Java any more for anything"

and finally::::::::::::"There is nothing that you can't do in Perl" ----> "I can challenge any one in the world for a better program in perl"

Love,
Ignaci

Re: 2009 is not a prime number. A python program to compute factors.

deeptext — Sun, 04 Jan 2009 18:08:19 -0000

Yes, and I needed to know. What is the smallest prime factor?
I guessed around: 7

(Also, your "copy to clipboard" links don't work for me).

Re: 2009 is not a prime number. A python program to compute factors.

Gerry B — Fri, 02 Jan 2009 19:45:00 -0000

There are supposed to be tab indentations. Not sure how to keep the tabs in a post

Re: 2009 is not a prime number. A python program to compute factors.

Gerry B — Fri, 02 Jan 2009 19:42:37 -0000

I just wrote this code (works in python 3.0 with the special "//" for division of integers). This code is much faster and will find your prime factors. I take advantage of the fact that 30=2*3*5, so any primes above 30 must be 1,7,11,13,17,23,or 29 modulo 30, otherwise the number would be divisible by 2,3 or 5. Here is the function:

def pfast(x):
remder = x
outcat="1"
while 1:
if remder%2==0:
outcat=outcat+"*2"
remder=remder//2
else:
break
while 1:
if remder%3==0:
outcat=outcat+"*3"
remder=remder//3
else:
break
while 1:
if remder%5==0:
outcat=outcat+"*5"
remder=remder//5
else:
break
while 1:
if remder%7==0:
outcat=outcat+"*7"
remder=remder//7
else:
break
while 1:
if remder%11==0:
outcat=outcat+"*11"
remder=remder//11
else:
break
while 1:
if remder%13==0:
outcat=outcat+"*13"
remder=remder//13
else:
break
while 1:
if remder%17==0:
outcat=outcat+"*17"
remder=remder//17
else:
break
while 1:
if remder%19==0:
outcat=outcat+"*19"
remder=remder//19
else:
break
while 1:
if remder%23==0:
outcat=outcat+"*23"
remder=remder//23
else:
break
while 1:
if remder%29==0:
outcat=outcat+"*29"
remder=remder//29
else:
break
c=0
while 1:
top = remder**0.5+1
c=c+30
if c>top:
return outcat+"*"+str(remder)
while 1:
if remder%(c+1)==0:
outcat=outcat+"*"+str(c+1)
remder=remder//(c+1)
else:
break
while 1:
if remder%(c+7)==0:
outcat=outcat+"*"+str(c+7)
remder=remder//(c+7)
else:
break
while 1:
if remder%(c+11)==0:
outcat=outcat+"*"+str(c+11)
remder=remder//(c+11)
else:
break
while 1:
if remder%(c+13)==0:
outcat=outcat+"*"+str(c+13)
remder=remder//(c+13)
else:
break
while 1:
if remder%(c+17)==0:
outcat=outcat+"*"+str(c+17)
remder=remder//(c+17)
else:
break
while 1:
if remder%(c+23)==0:
outcat=outcat+"*"+str(c+23)
remder=remder//(c+23)
else:
break
while 1:
if remder%(c+29)==0:
outcat=outcat+"*"+str(c+29)
remder=remder//(c+29)
else:
break

Re: 2009 is not a prime number. A python program to compute factors.

dnene — Fri, 02 Jan 2009 19:40:21 -0000

Blame it on google .. it got me the other link first :) and of course the fact that I wanted to get it done quickly. :)

Re: 2009 is not a prime number. A python program to compute factors.

wj32 — Fri, 02 Jan 2009 19:28:39 -0000

You didn't see my prime factorization code, then? http://wj32.wordpress.com/2007/12/08/prime-fact...

Re: 2009 is not a prime number. A python program to compute factors.

audax — Fri, 02 Jan 2009 19:10:36 -0000

[i for i in factor(int(sys.argv[index]))]
should be just list([factor(int(sys.argv[index])))

Re: 2009 is not a prime number. A python program to compute factors.

Gerry B — Fri, 02 Jan 2009 19:02:48 -0000

sorry I just realized I am using Python 3.0, which changed the rule for division compared to old Python. Now, to get what you did, the division sign is // and not simply /

Re: 2009 is not a prime number. A python program to compute factors.

Gerry B — Fri, 02 Jan 2009 18:30:31 -0000

How do you get Python to do more than 18 decimal places of accuracy in a division? When I try your algo I get the following factors:

[1037468051.0, 863693, 7, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 29]

Re: 2009 is not a prime number. A python program to compute factors.

dnene — Fri, 02 Jan 2009 17:07:43 -0000

I could've .. just chose n**0.5 instead of sqrt(n). Thats already in the code.

Re: 2009 is not a prime number. A python program to compute factors.

varun thacker — Fri, 02 Jan 2009 16:32:49 -0000

why dont you keep the limit variable to like sqrt(n).That can be the highest factor other than itelsf

regards,
Varun

Re: Will Rails go the Struts 1 way ?

dipankarsarkar — Mon, 29 Dec 2008 15:54:10 -0000

I would think that rails would dominate in the merging ... though there are some positives to be taken from the merb codebase ....

Re: Will Rails go the Struts 1 way ?

lowell — Fri, 26 Dec 2008 02:05:20 -0000

"I really cannot imagine easily merging two frameworks and have the best of both of them be reflected in the result "

Merb, to put it as simply as possible, is a pluggable, unopinionated, not-as-mature, but definitely usable version of Rails.

It isn't a merger of equals, Merb is being consolidated into Rails 3. I'm expecting Rails to support ORMs other than AR out of the box and to also support templating languages other than ERb out of the box (hopefully adding Haml). They're going to add a consistent API plugins and crap don't outdated with every point release.

Basically, it's going to have Rails try to cater to everything, which goes against the DHH's original vision. It's annoying, but there's no way I'm going to stop coding in Ruby - I've gotten too used to it. Besides, the move was to unify the existing Ruby community and to not confuse newcomers.

So, um. Yeah. What I was going to say before I got sidetracked is that no, merging them is not going to be as difficult as you might think as the two have much in common as it is (workflow-wise, not code-wise).

Re: Will Rails go the Struts 1 way ?

Caligula — Wed, 24 Dec 2008 19:17:48 -0000

There are more similarities between Rails/Merb than S1 and WW/S2.

Re: Java : the perpetually undead language

ranjan — Fri, 12 Dec 2008 13:44:23 -0000

I agree with you totally. There are people, companies and corporate who's survive because of Java. I admit, I've been lured by python, scala, groovy and all other languages which offer you syntactic nirvana, but none of them address issues that are so important to me and my customer who's day to day business depends on software. Imagine in case of some ( god forbid ) medical emergency you wanted money from ATM and you couldn't get it because some program written in fancy language crashed. I rather have an unproductive, ugly language on whom people can trust their money and lives with.

Re: A twitter feed in gmail : Write a google gadget

David Weller — Fri, 12 Dec 2008 10:33:37 -0000

awesome!!!

Re: A twitter feed in gmail : Write a google gadget

dnene — Thu, 11 Dec 2008 23:52:22 -0000

Not sure why its happening, but its happening for me as well. Shall need to
investigate.

Re: Java : the perpetually undead language

Tom — Thu, 11 Dec 2008 22:15:07 -0000

My examples were all cross platform, but I agree that there may be reasons (a big one for me being the pain of deploying cross-platform binaries vs. jars or html/js).

Re: Java : the perpetually undead language

Dave — Thu, 11 Dec 2008 21:51:42 -0000

Java in on track to becoming COBOL, and nobody wants to be a COBOL programmer, do they? Like C++ before it, Java will wane and plateau and eventually be relegated to legacy usage. Ruby seems likely to take over, but it, too, will go away for the next thing. But, it's not like it's going to happen tomorrow. I just think that Java Developers need to accept that Java will go away and something else will be where Java is now, and they ought to get on the stick to learn it.

Re: A twitter feed in gmail : Write a google gadget

Chef Tony — Thu, 11 Dec 2008 21:16:06 -0000

Great post here, I am learning to decipher basic code, but the fact that you link to yours is just great. I installed, but it did not ask me for user name and password, so it's blank. Any ideas?

Re: Java : the perpetually undead language

dnene — Thu, 11 Dec 2008 17:51:15 -0000

Your description of the cake is extremely well done. You've managed to comment on the underlying issues as well in a concise and effective fashion. Nicely put.

On a separate note, Python is an upstart that is older than Java.

Re: Java : the perpetually undead language

yason — Thu, 11 Dec 2008 17:33:06 -0000

To be direct, it's hard and partially impossible to compare those two languages because they're on different markets.

Nevertheless, Java has lost the bleeding edge: it has a stable market share on enterprise software but otherwise it's just catching up with the more advanced languages these days for the sake of the illusion that "Java evolves too. Really!".

It doesn't and it doesn't need to evolve; IMHO Java 1.4 delivered pretty much what you ever wanted from Java. The enterprise guys can get their comfy security without awkward adaptations of generics, closures and rest of the stuff that is copied from elsewhere. But you don't seem to get the interesting jobs with Java skills anymore and it's not the number one language if you want to learn new stuff. That's bad because if you're not riding on the wave that drives the new stuff you're being obsoleted. First slowly, then at once.

What Java has to do to survive is not technical. Technically, Java is good enough (or, not bad enough). But as it's the market leader on enterprise software it must reinvent itself on that very same market before some of the new languages come and eat the cake that currently belongs to Java. It could take five years, even less if Java doesn't fight back. On the other hand, if Java has already reinvented a new cake at that time, it's going to continue to lead the market to a new direction in the future.

And the name of the cake seems to be "secure, reliable, and not too smart enterprise solutions". By "not too smart" I mean something that can be practically averaged over dozens of developers. Python is smart because one whizbang Python hacker can rewrite and obsolete much of the Java stuff in one corporation, but they couldn't easily find a replacement for him when things turn boring. "Not smart" means low contribution rates per developer but lots of interchangable developers. The Java way. But with a new toolbox.

By the way, Python isn't an upstart: it's older than Java.

Re: Java : the perpetually undead language

Jamie McIlroy — Thu, 11 Dec 2008 16:18:38 -0000

I appreciate your approach to this ongoing subject. While the sport in me enjoys language feature vs. language feature debates, the pragmatic professional understands that comfort pays the bills. Customers want to be comfortable with their decisions. Well written.

Re: Java : the perpetually undead language

dnene — Thu, 11 Dec 2008 15:46:57 -0000

If we have access to such a rich english language why do we then end up confusing the middle aged and the dead ? This entire argument of then valuing only the youth which generally is the most vibrant and exciting stage substantially underemphasises the contributions that we make to society when in our middle ages.

I understand that some liberty can indeed by taken with the language and would assume that "dead" could cover cases where severe reduction in capabilities and importance into a vegetative state is near imminent. But java is not dead by that standards. I just think it is middle aged and has a long life ahead of it though all the excitement seems to be getting distributed amongst the newer kids on the block (often quite rightly so).