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simplify sinh expression

asked 2013-01-20 04:13:50 -0500

Dirk Danckaert gravatar image

updated 2013-01-20 04:15:49 -0500

I guess I just ran up against one of those maxima things again, but I thought I would signal the problem anyway.

I would have expected Sage to simplify

sinh(log(1+sqrt(2)))

(it is 1), but Sage doesn't. It doesn't return True to the following either

arcsinh(1)==1+sqrt(2)

or am I missing something?

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sinh(log(1+sqrt(2))).n() 1.00000000000000

achrzesz gravatar imageachrzesz ( 2013-01-20 04:49:07 -0500 )edit

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answered 2013-01-20 06:45:43 -0500

DSM gravatar image

Wouldn't be the worst thing in the world if someone had a look at our simplification heuristics. In the meantime:

sage: y = sinh(log(1+sqrt(2)))
sage: y.simplify_full()
sinh(log(sqrt(2) + 1))
sage: y.maxima_methods().exponentialize()
-1/2/(sqrt(2) + 1) + 1/2*sqrt(2) + 1/2
sage: y.maxima_methods().exponentialize().simplify_full()
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Really, we have to decide if we want complete granularity like Maxima, which leads to things without ambiguity because you would choose whether to use methods that "simplify" multivalued functions like log, or to continue our current point of adding more and more methods to simplification. I lean toward the latter, but maybe it's time to think about that again.

kcrisman gravatar imagekcrisman ( 2013-01-21 01:51:44 -0500 )edit

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Asked: 2013-01-20 04:13:50 -0500

Seen: 168 times

Last updated: Jan 20 '13