From: Yoshiki Tsunesada <ytsunesada@...>
Date: 2005-01-26T21:14:09+09:00
Subject: Re: Hacking NArray

  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);

On Wed, 26 Jan 2005 18:33:39 +0900, Brian Schr旦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