Re: algdep

[Igor Schein <igor@txc.com>]

On Tue, Jul 20, 1999 at 01:31:12PM -0700, Alexandru Ghitza wrote:
> Hello!
> 
> I keep on getting the message "***   precision loss in truncation" when I
> use algdep with degree larger than 10.  For instance,
> 
> ?
> algdep(-0.2355220940001195812949972500-0.03326199546780660561982976334*I,10)
>   ***   precision loss in truncation
> 
> Is there anything that I can do to resolve this situation?  Using algdep
> with a non-zero flag doesn't seem to be an option, since it never gave me
> the correct answer in this range.
> 
> Thank you,
> Alexandru Ghitza
> 

Playing a bit more with algdep(), I came across this bug:

? \p
   realprecision = 28 significant digits
? algdep(1/2+I/3,16)
18*x^9 + 7*x^8 - 10*x^7 + 12*x^5 - 6*x^4 + 3*x^3 + 7*x^2 + 5*x + 3
? \p9
   realprecision = 9 significant digits
? algdep(1/2+I/3,16)
  ***   the PARI stack overflows !!!
 
  ***   Warning: doubling stack size; new stack = 8000000.
? \p28
   realprecision = 28 significant digits
? algdep(1/2+I/3,16)
  ***   overflow in R*R

Thanks

Igor