Mike McLendon on Wed, 26 May 2010 14:54:32 +0200

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Re: setseriesprecision in library mode

Changing the global variable "precdl" did exactly what I wanted.
Thanks for the quick reply!

On 5/25/10, Bill Allombert <Bill.Allombert@math.u-bordeaux1.fr> wrote:
> On Tue, May 25, 2010 at 06:22:05PM -0400, Mike McLendon wrote:
>> Hi,
>> I'm using the PARI library and would like to increase the series
>> precision.  I see that there is a prototype of a function called
>> "setseriesprecision" in the paridecl.h header file under the
>> /*default.c*/ comment.  However, the "default.c" source code file does
>> not implement the "setseriesprecision" function.  (Though it does
>> implement the "getrealprecision" and "setrealprecision" functions,
>> both of which I can use in my code.)  I'm using pari-2.3.5 (stable).
> Yes, you can change the global variable precdl.
> This is more or less documented in the file
> src/functions/programming/default
> (If you compile default(seriesprecision,30); with GP2C, you get
> precdl = 30;)
> I recorded this error in paridecl.h, thanks.
>> I would like to increase the series precision so that functions like
>> tan(x) are more accurate when using the "gtopoly" function to convert
>> the series to a poly and then the "gsubstr" function to evalute the
>> poly at specific values.  Perhaps the is also another way to do this?
>> Any help would be appreciated.  Thanks!
> Well, another way would be to convert your polynomial to a series with
> the right precision before calling gtan(x), for example:
> gtan(poltoser(x,varn(x),n)) where is the precision you want.
> Cheers,
> Bill.