Large errors for eint()

[Jeroen Demeyer <jdemeyer@cage.ugent.be>]

It seems that the eint() function can have quite large errors in its 
approximation.

Just one example with a relative error of over 28 bits:
gp> \p 481
   realprecision = 481 significant digits
gp> x = eint1(15);
gp> \p 500
   realprecision = 500 significant digits
gp> y = eint1(15);
gp> (x-y)/x * 2^1600
%19 = 418655076.1440077999

With the vector version of eint1, errors can be even larger.

Do you consider this a bug?

Cheers,
Jeroen.