FW: [PATCH] Bug #24064: Standard deviation

Quickly checked out the patch and first thing to catch my eye
was the use of '//' comments. That's a big no-no. (this is not C++)
Please read the CODING_STANDARDS couple of times. :)

(Use of these C++ comments causes compile failure with some compilers)

--Jani
       

Er, either the php-internals MARC archive doesn't show all attachments, or
my diff file got stripped en route for not having a .txt extension. I've
attached it again, just to make sure.

Paul

-----Original Message-----
From: Paul Hudson [mailto:webjedi@hudzilla.eclipse.co.uk]
Sent: 10 February 2004 00:30
To: 'internals@lists.php.net'
Subject: [PATCH] Bug #24064: Standard deviation

Hi there,

Bug #24064 (submitted by tularis@php.net) requests a standard deviation
function for PHP. I realise that any of you could implement this in 10
minutes, but according to the bug database it is still Open so I figured I
would give it a try myself!

There are probably a dozen errors in the code and/or places where it could
be better optimised, but I'm hoping one of you might be able to help with
that. So, the attached diff file implements the function array_std_dev(),
to calculate standard deviation using the deviation method.

With the function in place, standard deviation is calculated like this:

<?php
$scores = array(18,5,7,18,3,2,10);
print array_std_dev($score);
// prints 6.6833125519211
?>

My first attempt at implementing this was using an extra array to buffer the
deviations - this was more out of curiosity to see how the array stuff
works. Sadly, it caused PHP to segfault and I couldn't figure out why - can
any of you help me spot the brain fart? (I've attached the offending code
in bad_stddev_code.txt)

Yours,

Paul

PS: I'm not on the internals list, so I would appreciate it if you would CC
me on your reply.

Hi,
as Derick stated 2 days ago, the problem is not in the extension but in the
MIME header. The attachment must be text/plain.

Andrey

Quoting Paul Hudson webjedi@hudzilla.eclipse.co.uk:

Er, either the php-internals MARC archive doesn't show all attachments, or
my diff file got stripped en route for not having a .txt extension. I've
attached it again, just to make sure.

Paul

-----Original Message-----
From: Paul Hudson [mailto:webjedi@hudzilla.eclipse.co.uk]
Sent: 10 February 2004 00:30
To: 'internals@lists.php.net'
Subject: [PATCH] Bug #24064: Standard deviation

Hi there,

Bug #24064 (submitted by tularis@php.net) requests a standard deviation
function for PHP. I realise that any of you could implement this in 10
minutes, but according to the bug database it is still Open so I figured I
would give it a try myself!

There are probably a dozen errors in the code and/or places where it could
be better optimised, but I'm hoping one of you might be able to help with
that. So, the attached diff file implements the function array_std_dev(),
to calculate standard deviation using the deviation method.

With the function in place, standard deviation is calculated like this:

<?php
$scores = array(18,5,7,18,3,2,10);
print array_std_dev($score);
// prints 6.6833125519211
?>

My first attempt at implementing this was using an extra array to buffer the
deviations - this was more out of curiosity to see how the array stuff
works. Sadly, it caused PHP to segfault and I couldn't figure out why - can
any of you help me spot the brain fart? (I've attached the offending code
in bad_stddev_code.txt)

Yours,

Paul

PS: I'm not on the internals list, so I would appreciate it if you would CC
me on your reply.

Hi Paul,
may you compile your PHP binary with --enable-debug and after that run your
sample scrit for once. See if there are leaks.

Andrey

Quoting Paul Hudson webjedi@hudzilla.eclipse.co.uk:

Er, either the php-internals MARC archive doesn't show all attachments, or
my diff file got stripped en route for not having a .txt extension. I've
attached it again, just to make sure.

Paul

-----Original Message-----
From: Paul Hudson [mailto:webjedi@hudzilla.eclipse.co.uk]
Sent: 10 February 2004 00:30
To: 'internals@lists.php.net'
Subject: [PATCH] Bug #24064: Standard deviation

Hi there,

Bug #24064 (submitted by tularis@php.net) requests a standard deviation
function for PHP. I realise that any of you could implement this in 10
minutes, but according to the bug database it is still Open so I figured I
would give it a try myself!

There are probably a dozen errors in the code and/or places where it could
be better optimised, but I'm hoping one of you might be able to help with
that. So, the attached diff file implements the function array_std_dev(),
to calculate standard deviation using the deviation method.

With the function in place, standard deviation is calculated like this:

<?php
$scores = array(18,5,7,18,3,2,10);
print array_std_dev($score);
// prints 6.6833125519211
?>

My first attempt at implementing this was using an extra array to buffer the
deviations - this was more out of curiosity to see how the array stuff
works. Sadly, it caused PHP to segfault and I couldn't figure out why - can
any of you help me spot the brain fart? (I've attached the offending code
in bad_stddev_code.txt)

Yours,

Paul

PS: I'm not on the internals list, so I would appreciate it if you would CC
me on your reply.

Hi Paul,

Why are you comparing, copying and converting each array element twice ?
There should be a more elegant way to do this.

--
Ard