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Re: Handling branch cuts in trig functions
Posted:
Mar 24, 2013 7:39 AM


On 3/24/2013 5:26 AM, G. A. Edgar wrote: > In article <kimdsn$lj3$1@speranza.aioe.org>, Nasser M. Abbasi > <nma@12000.org> wrote: > > >> >> I think now that answer to sqrt(sec(x)^2) should be >> sec(x) without need to give the branch. > > That answer is incorrect for complex x ... so to get that answer in > Maple, you must assume x is real. > > simplify(%) assuming x::real; >
But I am using Maple 17?
 ans:=simplify(sqrt(sec(x)^2)) assuming x::positive;
1  cos(x)
simplify(abs(sec(x)) ans); 0

Unless x::positive implies x::real (since positive does not apply to complex numbers). Is this what you meant? I get same result using x::positive or x::real.
So Maxima was wrong then:
sqrt(sec(x)^2); sec(x)
No assumptions!
thanks, Nasser



