Re: experimental localprec() feature

[Loïc Grenié <loic.grenie@gmail.com>]

2014-10-09 17:37 GMT+02:00 Bill Allombert <Bill.Allombert@math.u-bordeaux.fr>:
> Dear PARI developpers,
>
> I have created an experimental git branch bill-localprec that adds a command
> localprec() which allow to set the real precision locally:
>
> Consider the function:
> f(s)=Pi^s
> and
> s=precision(1.,100)
>
> Pi is computed using the current precision.
> If we want the resut to be correct to the precision of s,
> we could do
>
> g(s)=
> { my(prec=default(realprecision));
>   default(realprecision,precision(s));
>   my(r=Pi^s);
>   default(realprecision,prec);
>   r;
> }
>
> which is rather cumbersome. Using localprec() it is sufficient to say:
>
> g(s)=localprec(precision(s));Pi^s
>
> Also it is safer since the value of realprecision is restored even if an error
> occurs.

     Nice! Thanks! That's something that I have dreamed for a long time.

             Loïc