#14591: cosh integral incorrect because of abs_integrate
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Reporter: kcrisman | Owner: burcin
Type: defect | Status: new
Priority: major | Milestone: sage-6.3
Component: calculus | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Comment (by pbruin):
The answer cosh(''x'') is completely wrong, even in a neighbourhood of
''x'' = 0:
{{{
cosh(x) = integrate(sqrt(1 - 1/4*cosh(x)^2),x)
=> sinh(x) = sqrt(1 - 1/4*cosh(x)^2)
=> sinh(x)^2 = 1 - 1/4*cosh(x)^2
=> 0 = 3/4 (substitute x = 0)
}}}
According to the ask.sagemath.org link in the ticket description, the
correct answer can be expressed in terms of an exponential integral
function, which I trust much more.
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Ticket URL: <http://trac.sagemath.org/ticket/14591#comment:7>
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