Phil Dawes' Stuff - Latest Comments

Re: The Factor Attraction

Roger Levy — Tue, 02 Jun 2009 22:05:31 -0000

Hi,

Do you feel that your agility in Factor has improved since this post?

Roger

Re: Disqus comments

phildawes — Mon, 11 May 2009 07:44:21 -0000

Thanks for the pointer - I've cleaned up the spam and regrettably added some moderation

Re: Disqus comments

Dominic Sayers — Mon, 11 May 2009 06:07:24 -0000

I'm loving the comments thread for this post. Can't decide whether to get my upholstery cleaned or do something about my fast food obesity.

Re: Factor makes you write better code

phildawes — Sun, 12 Apr 2009 14:57:30 -0000

Cool - thanks Eric

Re: Factor makes you write better code

Eric Mertens — Sun, 12 Apr 2009 03:25:21 -0000

I pasted some code that does the moving sum in factor.

http://paste.factorcode.org/paste?id=569#282

Re: Factor makes you write better code

phildawes — Tue, 31 Mar 2009 08:54:52 -0000

This comment on proggit was particularly good I thought

Re: Factor makes you write better code

phildawes — Tue, 31 Mar 2009 05:26:48 -0000

More discussion at proggit

Re: Factor makes you write better code

Alex13 — Tue, 31 Mar 2009 02:16:54 -0000

Here is moving average in J:

[arr =. i.10
0 1 2 3 4 5 6 7 8 9

ave =. +/%#

4 ave \ arr
1.5 2.5 3.5 4.5 5.5 6.5 7.5

Re: Factor makes you write better code

Sam Danielson — Mon, 30 Mar 2009 21:24:59 -0000

I think you can eliminate the inner loop by storing a "moving" sum. I'm sorry but I don't know how to put this into factor.

var sum = 0;
for (i=0; i<arr.length; i++) {
if (i >= period) sum -= arr[i - period];
sum += arr[i];
out.push (sum / period);
}

Re: And another new programming language

Jeff — Fri, 13 Mar 2009 21:00:20 -0000

I'm still looking for a minimal machine that supports true hardware parallelism. Any thoughts? Pointers?

Re: Spread Betting

Lorraine — Mon, 26 Jan 2009 16:51:30 -0000

How is it going, a few weeks later?

Re: Spread Betting

Andy — Tue, 16 Dec 2008 19:19:03 -0000

nice read i understand your pain about requiring compliance permission for each trade as i used to work for a brokerage company and had the same problem, the current system is pretty ridiculous - at the time i used to trade forex which didn't require disclosure ;)

Andy

http://www.financial-spread-betting.com

Re: Disqus comments

phildawes — Thu, 02 Oct 2008 10:19:14 -0000

Thanks for pointing me at your script - I'll defo check it out

Re: Really simple html templating in factor

Slava Pestov — Thu, 02 Oct 2008 05:24:14 -0000

Phil, by sheer coincidence, Doug Coleman (erg) implemented something similar in extra/interpolate. He's using it to construct SQL stored procedures, IIRC. Perhaps you could look at his code for ideas, or merge your efforts? On a related note, I'd love to have your work (possibly after refactoring it to use 'interpolate') in the repository under basis/html/templates/simple, or something like that. Having more options for templating is always good.

Re: Disqus comments

davemw — Wed, 01 Oct 2008 11:24:21 -0000

For the past 5 years my blog has consisted of a gently accumulating Python script. It is currently around 300 lines, up from 200 or so when I initially created it. Around 2006 I decided to write a script to import the (filesystem-based) articles into a WordPress install. Instant dissatisfaction. WordPress is huge, insecure, and a little overfeatured for the average Joe.

So I'm still here with my horrible little Python script, and quite happy to be using it over WordPress. I'm presently adding an archives facility, integration with Disqus, and my first attempt at a pretty theme.

Take a look, it does HTML and RSS 2.0 output, and supports either HTML or a horrible wiki-like formatting for posts:

http://pastebin.com/f1be9ea59

Re: Really simple html templating in factor

ryantm — Tue, 30 Sep 2008 17:25:02 -0000

Have you seen Haml? It's a templating language that makes some complex control stuff with HTML or XML look good. I'm not really sure how it would integrate with Factor evaluation methods though.

http://haml.hamptoncatlin.com/

Re: Searching arrays in X86 assembler with a bloom filter pt 3

Phil Dawes — Sat, 13 Sep 2008 06:30:13 -0000

Slava Pestov wrote:
> Hi Phil,
>
> I couldn't post a comment on your blog for some reason so I'm posting
> this to the list instead.
>
> The seq>hash word you write already exists in the sets vocabulary, its
> called unique.
>
> And (prepare-filter) looks nicer if you use fry:
>
> : (prepare-filter) ( filter seq -- )
> '[ 1048576 mod _ set-bit ] each ;
>
> Slava

Re: Searching arrays in X86 assembler with a bloom filter pt 3

Phil Dawes — Sat, 13 Sep 2008 06:29:11 -0000

@Asm - thanks for the link, that's a handy resource

Re: Searching arrays in X86 assembler with a bloom filter pt 3

Asm — Fri, 12 Sep 2008 19:44:30 -0000

Variable shifts have the count in %cl.

But why bother? bt r,r and bt r,i are only 1 uop on a Core2. Check the instruction timings here: http://www.agner.org/optimize/

Use mov (%eax,%edi,4), %edi and drop the shl $0x2, %edi.

Re: Searching arrays in X86 assembler with a bloom filter pt 3

Anonymous — Fri, 12 Sep 2008 19:15:20 -0000

You can shift by the contents of the CL register, e.g. shl %cl, %eax .

Re: Searching arrays in X86 assembler with a bloom filter pt 2

Phil Dawes — Fri, 12 Sep 2008 09:21:58 -0000

Thanks for the tip Asm. It seems pretty quick but I'll try the ANDing and SHRing approach to see how it compares

Re: Searching arrays in X86 assembler with a bloom filter pt 2

Asm — Fri, 12 Sep 2008 07:55:07 -0000

BT is slow for m, r operands. 12 uops on a P4. 10 uops on a Core2. Avoid.

Re: Searching arrays in X86 assembler with a bloom filter pt 2

Phil Dawes — Fri, 12 Sep 2008 06:33:13 -0000

Hi Kieran! I'm expecting thousands occasionally. Hundreds commonly.

Re: Searching arrays in X86 assembler with a bloom filter pt 2

Kieran — Fri, 12 Sep 2008 06:26:57 -0000

Hello, you've said there are around 12M elements in the array, but how many are you expecting in the set? Tens? Hundreds? Thousands?

Re: Searching arrays in X86 assembler with a bloom filter

jsh — Thu, 11 Sep 2008 20:45:00 -0000

did you try a judy array?

http://judy.sourceforge.net/