From: "Brian Schröder" <ruby@...>
Date: 2005-01-26T21:29:50+09:00
Subject: Re: Hacking NArray

On Wed, 26 Jan 2005 21:14:09 +0900
Yoshiki Tsunesada <ytsunesada@yahoo.co.jp> wrote:

>   Brian,
> 
>   Adding methods to NArray object is rather simple:
> If an object is of double float,
>   
> static VALUE my_narray_abs_in_place(VALUE self)
> {
>   struct NARRAY *na;
>   double *ptr;
>   int i, n;
>   GetNArray(self, na);
>   n = na->total;
>   ptr = (double*) na->ptr;
>   for (i = 0; i < n; i++) ptr[i] = fabs(ptr[i]);
>   return self;
> }
> 
> and,
> 
>   rb_define_method(cNArray, "abs!", my_narray_abs_in_place, 0);
> 

Thank you for this information. It is very helpfull. Maybe it should be included onto the website?

best regards,

Brian Schr�der

> On Wed, 26 Jan 2005 18:33:39 +0900, Brian Schr��der wrote:
> > On Wed, 26 Jan 2005 09:26:50 +0900
> > Yoshiki Tsunesada <ytsunesada@yahoo.co.jp> wrote:
> > 
> >>>  than I thought. I would really appreciate an example on how to extend
> >>>  narray. That would be: 
> >>>  - How to create a function that works on one or more arrays (in
> >>>  place|with copy), one element at a time
> >>>  - How to create a function that works on one or more arrays with random
> >>>  access to the entries.
> >>    Could you show Ruby code you expect to work with it ?
> >>  
> >>    Yoshiki
> >>  
> > 
> > Well:
> > 
> > a.abs! 
> > 
> > for example.
> > 
> > And something like:
> > 
> > define_inplace_operator 'abs!', {[[:float, :float], [:double, 
> > :double], [:int, :int]] => '*p = *p > 0 ? p : -p;'}
> > 
> > in the mkop.rb skript to create those functions automatically in the 
> > c source.
> > 
> > That would be a nice dream...
> > 
> > But at the moment I'll try to go with the other advice and implement 
> > my own purely double based volume class. (And with code generation 
> > maybe also float, int etc, but I have to do some exploration first, 
> > as I've never written a c extension.
> > 
> > Regards,
> > 
> > Brian
>