Ask Your Question
1

Setting Precision in Sage

asked 2010-08-30 16:27:44 +0100

willmwade gravatar image
integral(integral(e^(-0.00260657639223762*(h - 11.1600000000000)^2 - 1.34372480515*(d - 2.85000000000000)^2)/pi, d, 0,Infinity), h, 0, Infinity).n()

I have been working through an error I am receiving with the above command. The error I get when I run it is:

TypeError: Error executing code in Maxima
CODE:
    sage297 : integrate(sage293,sage294,sage295,sage296)$
Maxima ERROR:

rat: replaced -0.0026065763922 by -200/76729 = -.00260657639223762

rat: replaced -11.16 by -279/25 = -11.16

rat: replaced -1.343724 by -3233/2406 = -1.34372402327515

rat: replaced -2.85 by -57/20 = -2.85
Maxima encountered a Lisp error:

 5883790627 is not of type FIXNUM.

Automatically continuing.
To enable the Lisp debugger set *debugger-hook* to nil.

However if I shorten the decimals to something like:

integral(integral(e^(-0.0026*(h - 11.1600000000000)^2 - 1.343724*(d - 2.85)^2)/pi, d, 0,Infinity), h, 0, Infinity).n()

Then the command runs fine without any issues. Now perhaps this is a bug, but really I do not need the level of precision that is in these commands. Of course I do not want numbers here but variables and it is evaluating the variables to this level of precision that is causing the issue. For example I say:

sage: f(d,h) = (1/(2*pi*0.61*13.85))*exp(-1/2*((d-2.85)^2/0.61^2+(h-13.85)^2/13.85^2))
sage: f
(h, d) |--> 0.05918210333195241758892111025625850742735*e^(-0.002606576392237615503916381029337017294634*(h - 11.16000000000000000000000000000000000000)^2 - 1.343724805159903251814028486965869389949*(d - 2.850000000000000000000000000000000000000)^2)/pi

Any ideas? P.S. I have searched around, but I have not found any that apply to just basic numbers in Sage.

edit retag flag offensive close merge delete

Comments

Since this appears to be happening entirely in maxima, you might want to ask on the maxima list...

William Stein gravatar imageWilliam Stein ( 2010-08-30 17:38:22 +0100 )edit

1 Answer

Sort by ยป oldest newest most voted
1

answered 2010-08-30 18:01:27 +0100

niles gravatar image

Strange, I don't seem to have trouble with

sage: integral(integral(e^(-0.00260657639223762*(h - 11.1600000000000)^2 - 1.34372480515*(d - 2.85000000000000)^2)/pi, d, 0,Infinity), h, 0, Infinity).n()
13.3454645567847

or

sage: f(d,h) = (1/(2*pi*0.61*13.85))*exp(-1/2*((d-2.85)^2/0.61^2+(h-13.85)^2/13.85^2))
sage: integral(integral(f(d,h), d, 0,Infinity), h, 0, Infinity).n()
0.841343497874347

however, the answer to problems with symbolic integration and then numerical evaluating suggests using .n(prec) or RealIntervalField(prec) so, for example, you could try

sage: integral(integral(e^(-0.00260657639223762*(h - 11.1600000000000)^2 - 1.34372480515*(d - 2.85000000000000)^2)/pi, d, 0,Infinity), h, 0, Infinity).n(prec=12)
13.3
sage: integral(integral(f(d,h), d, 0,Infinity), h, 0, Infinity).n(prec=12)
0.842

sage: RealIntervalField(12)(integral(integral(f(d,h), d, 0,Infinity), h, 0, Infinity).n()) 
0.842?
sage: RealIntervalField(30)(integral(integral(f(d,h), d, 0,Infinity), h, 0, Infinity).n()) 
0.841343498?

(does the RealIntervalField(12) answer indicate an error in RealIntervalField() !?)

edit flag offensive delete link more

Comments

Hmm... I still get the same error with your options. Perhaps I broke something while trying to fix the problem. Any way to reset everything? Note I tried reset() and it still produced the error.

willmwade gravatar imagewillmwade ( 2010-08-31 08:37:30 +0100 )edit

I'm afraid the best I could try is quit and restart sage; if you're using the notebook, start a fresh worksheet. If you've already tried these, my next line of defense would be reinstall sage, but you should probably ask a new question here to see if other people have better ideas!

niles gravatar imageniles ( 2010-08-31 08:55:24 +0100 )edit

I found out how. Deleting ~/.sage did it. rm -Rf ~/.sage

willmwade gravatar imagewillmwade ( 2010-08-31 14:04:46 +0100 )edit

test comment

Evgeny gravatar imageEvgeny ( 2010-08-31 19:01:12 +0100 )edit

Your Answer

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

Add Answer

Question Tools

Stats

Asked: 2010-08-30 16:27:44 +0100

Seen: 1,283 times

Last updated: Aug 30 '10