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simplifying out negative signs in exponents

asked 2018-07-24 16:19:26 -0500

Jason021 gravatar image

Hello all!

I can't for the life of me find a way to force sage to return terms with only positive coefficient variable exponents. For example, if I enter something like

assume(n, 'integer', n>10)
c = 2^(-n)

I would like the output to be something like 1/(2^n), but instead I can only get something like 2^(-n). Is there a way to force the output to display only positive coefficients in front of the n?

In general I'd like some magicFunc function which I could feed some expression g(x,n) and have it return a rational expression with no negatives; eg.

var('x,n')
assume(x,'real')
assume(n,'integer',n>10)
g(x,n) = 2^(-n)*x^(-3*n)*3^n
magicFunc(g(x,n))

Would return 3^n/(2^n*x^(3n))

Is this possible? This seems like it should be an existent simplification method, but nothing I've tried seems to work.

Thanks!

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Comments

What version of Sage are you using? Type version() at the Sage prompt.

slelievre gravatar imageslelievre ( 2018-07-24 18:08:11 -0500 )edit

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answered 2018-07-24 17:34:57 -0500

tmonteil gravatar image

Isn't this the case already ? On my laptop (SageMath version 8.3.rc2), i have:

sage: var('x,n')
....: assume(x,'real')
....: assume(n,'integer',n>10)
....: g(x,n) = 2^(-n)*x^(-3*n)*3^n
(x, n)
sage: g
(x, n) |--> 3^n/(2^n*x^(3*n))

sage: c = 2^(-n)
sage: c
1/(2^n)
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Asked: 2018-07-24 16:19:26 -0500

Seen: 24 times

Last updated: Jul 24