[CLN-list] Types in cl_R

[Isidro Cachadiña Gutiérrez]

El Miércoles, 17 de Noviembre de 2004 22:28, Richard B. Kreckel escribió:
> On Tue, 16 Nov 2004, Isidro [iso-8859-15] Cachadiña Gutiérrez wrote:
> > I am using cln with real numbers. I have a problem in the expt
> > function...
>
> [...]
>
> > I also can define this function as:
> >
> > cln::cl_R expt(cln::cl_R x, cln::cl_R y)
> > {
> >   return exp(x*ln(y));
> > }
> >
> > And It works fine,  but I think that It have to be defined somewhere in
> > the library.
>
> Well, only if `x' is positive, right?
This is ok because the result is a complex number.
> Or if `y' is integer. 
No, y can be a real  number.  There isn't any problem with this.  

Normally if you are using real numbers you don't expect to find things like
this -5.34^7.32.  Perhaphs it would be neccesary a warning in the function to 
prevent it uses with x<0.

> Maybe it would be worthwhile though, considering the fact that we also
> have sqrt(cl_R) defined only for arguments >= 0 without type checks for
> that.  But given the other signatures, I see only very limited use.

Where you see a limited use I see a mathematical consistency use.    If you 
are working with real number, you don't expect  complex numbers arriving 
elsewhere, or better, you have to know where there is the posibility to find 
a result that leads to complex numbers.  I prefer an error warning if 
something like sqrt(-1) happen.

Saludos. 
>
> Saludos
>  -richy.

-- 
***************************************************************************
*                    Dr. Isidro Cachadiña Gutiérrez                       * 
*                        Departamento de Física                           * 
*                         Facultad de Ciencias                            *
*                      Universidad de Extremadura                         *
*                        06071  Badajoz ( SPAIN )                         * 
*                         email: icacha at unex.es                           * 
*    Teléfono: +34 924 289 300 Ext. 6826     Fax: +34 924 289 651   *
***************************************************************************
* Usuario Linux: 8569         *
* Para clave pública GnuPG: http://onsager.unex.es/firma.pub.asc          *
***************************************************************************
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: not available
Url : http://www.cebix.net/pipermail/cln-list/attachments/20041118/d02719fc/attachment.pgp