Mike Hansen schrieb:
On Sat, Apr 10, 2010 at 3:37 AM, bb <bblo...@arcor.de> wrote:
sage: n(sqrt(2.), digits=40)
1.414213562373095145474621858738828450441
sage: n(sqrt(2), digits=40)
1.414213562373095048801688724209698078570
sage:
If you wanted this to be more like Maxima, the appropriate thing to do
would some something like:
sage: RealNumber = RealField(137)
sage: sqrt(2.0)
1.414213562373095048801688724209698078570
sage: sqrt(2).n(digits=40)
1.414213562373095048801688724209698078570
Sage is missing the errror forwarding of Mathematica.
Yes, Sage does not have a numerical type that does Mathematica's
significance arithmetic. An interesting thread about the merits and
demerits of significance arithmetic is
http://sci.tech-archive.net/Archive/sci.math.symbolic/2008-03/msg00014.html
.
One could do a little work to get Sage's interval arithmetic to do
something similar.
--Mike
Tnx for helping. I did some more experimentation. I dont want to bother
you, but if you have some time and some pation I would be thankfull for
one more explanation. Your tip works as expected, but if I use the
method n() I still get 53 bit of significant bits??? (see last
expression of the snippet.)
I argue, that the parameter of n() is set elsewhere in another Variable
than RealNumber?
sage: RealNumber = RealField(137)
sage: sqrt(2.)
1.414213562373095048801688724209698078570
sage: _.prec()
137
sage:
sqrt(2.0000000000000000000000000000000000000000000000000000000000000000000)
1.414213562373095048801688724209698078570
sage: _.prec()
137
sage:
n(sqrt(2.0000000000000000000000000000000000000000000000000000000000000000000),
digits=60)
1.41421356237309504880168872420969807856967336610324780267484
sage: _.prec()
203
sage:
n(sqrt(2.0000000000000000000000000000000000000000000000000000000000000000000))
1.41421356237310
sage: _.prec()
53
sage:
Regards BB
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