sorry for the late reply, at the moment I'm a bit busy finishing one
As Rolf wrote, Calc uses PowerSimplify which uses PowerExpand. The
latter can either assume that everything is real (default behaviour) or
use general expansion formulas if the arguments might be complex (which
we have now). Unfortunately, in this case PowerExpand doesn't take
$Assumptions into account.
I think that the simplest solution would be to make Calc and
PowerSimplify accept the Assumptions option which will be then passed to
PowerExpand. Then it will be up to the user to specify the assumptions.
As a workaround for now,
Sqrt[x - 1] // Calc // Simplify
returns the correct result, as Simplify always honors $Assumptions.
I'll fix this soon.
Am 14.09.2015 um 10:58 schrieb Rolf Mertig:
> This is due to me. Sorry.
> Somehwere internally PowerSimplify is used which assumes all variables are real. Maybe this assumption is not correct in general, of course. I mentioned this to Vladyslav and he will look into how to fix this. Sorry, but I have no time right now.
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