From help-octave-request at bevo dot che dot wisc dot edu  Fri Jan  8 04:21:51 1999
Subject: Re: Existence of a variable
From: Pablo Ledesma <pablole at ing dot uc3m dot es>
To: Daniel Tourde <ted at ffa dot se>
cc: help-octave at bevo dot che dot wisc dot edu
Date: Fri, 8 Jan 1999 11:12:40 +0100 (CET)

Hi Daniel,

try with

if (exist('b'))
   if (b) 
...

-------------------------------------------------------------------------
Pablo Ledesma Larrea                     Universidad Carlos III de Madrid
Butarque 15, 28911 Leganes, Madrid Spain       Email: pablole at ing dot uc3m dot es
-------------------------------------------------------------------------

On Fri, 8 Jan 1999, Daniel Tourde wrote:

> Hi !
> 
> I'm using a function defined like this
> 
> function F = f(a,b)
>   ...
>   if (b)
>     ...
>   endif
> endfunction
> 
> I want to call the function f with one or two parameters (A = f(a) or B
> = f(a,b))
> Then I have a problem because in the first case b is not defined and
> Octave complains. I tried to use the built-in function 'exist'
> 
> I hoped that exist(b) will give me 0 or 1 as explained in the help.
> Unfortunately, when I type exist(b), Octave complains and tell me that b
> does not exist, which is what I want to test, the existence of the
> variable b. I do not obtain the 0 value whuch would have been useful in
> a test like this
> 
> if (exist(b))
>    if (b) 
> ...
> 
> 
> Does anyone has an idea about how I could solve this problem ?
> 
> Thanks in advance for any information.
> 
> Best regards
> 
> 
> 			Daniel Tourde
> -- 
> ***********************************************************************
> Daniel TOURDE                                   E-mail : ted at ffa dot se
> The Aeronautical Research Institute of Sweden   Tel : +46 8 55 54 93 44
> P.O. Box 11021 S-161 11 BROMMA, Sweden          Fax : +46 8    25 34 81
> ***********************************************************************
> 
>