Arbitrary precision with power function

asked 2013-02-08 21:53:21 +0200

PlezzeR
3 ●1 ●1 ●3

Hello! Sorry for my english. Why in Sage 5.6

numerical_approx((3**2.72), digits=200)

gives

19.850425152727527944307439611293375492095947265625000000000000000000000\ 000000000000000000000000000000000000000000000000000000000000000000000000\ 000000000000000000000000000000000000000000000000000000000

and

RealField(1000)(3**2.72)

gives

19.850425152727527944307439611293375492095947265625000000000000000000000\ 000000000000000000000000000000000000000000000000000000000000000000000000\ 000000000000000000000000000000000000000000000000000000000000000000000000\ 000000000000000000000000000000000000000000000000000000000000000000000000\ 0000000000000

? After digit 5 zero, zero, zero. How to get more digits in Sage?

answered 2013-02-08 23:41:50 +0200

ppurka
2111 ●17 ●38

updated 2013-02-09 00:01:19 +0200

You have lost precision in the exponent. Use this instead:

sage: RealField(1000)(3**RealField(1000)(2.72))
19.8504251527275236501169613591809343996536832818298893731367232890539239539110192928936229752670609756876526611313601647375707220812753965333394338326864664393162650498858490630921586590646536288686549507904739021525557865246462265058167658909360187069317683688989045025859261795668964872237430699403

EDIT: In general, I think you need to ensure that you don't try to get higher precision after your computations. Rather, start with the higher precision from the very beginning.

edit flag offensive delete link

Comments

I understand. Thank you! It's work. Also example for maxima: fpprec:5000; bfloat(3.0b0 ^ 2.72b0); Example for GP/PARI: \p 1000 3^2.72

PlezzeR ( 2013-02-11 10:08:48 +0200 )edit

Is there a way to choose a default precision such that one does not need to keep typing RealField(1000)?

Mafra ( 2017-03-29 00:21:57 +0200 )edit

add a comment

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Arbitrary precision with power function

1 Answer

Comments

Your Answer

Question Tools

Stats

Related questions

Arbitrary precision with power function edit

1 Answer

Comments

Your Answer

Question Tools

Stats

Related questions

Arbitrary precision with power function