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Symbolic product in Sage?

asked 12 years ago

bk322 gravatar image

Suppose I'd like to compute

prod(1/x^4, x, 1, oo)

How can this be done?

I found an old thread, but with no answers.

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answered 12 years ago

benjaminfjones gravatar image

Take the natural logarithm of your product and you get a sum which can be evaluated:

ln(kx=11x4)=kx=1ln(1x4)

... now take the limit as k:

sage: sum(ln(1/x^4), x, 1, oo)
-Infinity
sage: e^sum(ln(1/x^4), x, 1, oo)
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answered 4 years ago

slelievre gravatar image

updated 4 years ago

In Sage, sum serves both for Python sums and for symbolic sums, but for products we have prod and product.

sage: product(1/x^4, x, 1, oo)
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This should be better documented... See

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answered 12 years ago

I have the same problem. If someone know how to do

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answered 12 years ago

asteve gravatar image

updated 12 years ago

Mike Hansen gravatar image

I found symbolic sum but not symbolic product in the reference files. I need to be able to classify a function of a erratic x which involve several symbolic foodstuffs from 1 to n or whatever. I then want to be able to do a derivative and a limit of this. I am trying out Sage because Mathematical doesn't seem to be able to handle this stuff exactly. I can define the function just fine but when I try to take the limit Mathematical can't seem to handle it.

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Am... Great, but why post it here?

bk322 gravatar imagebk322 ( 12 years ago )

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Asked: 12 years ago

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Last updated: Apr 16 '20