I don't know why they decided not to nomalize the result in a symbolic. Maybe they thought it was only important for numeric results.
You can get the result you expect if you first enter (-1,-1) and then do ARG. You'll get a numeric which you can convert to the desired symbolic with an XQ or a ->Q(pi) operation.
You also can use XQ to convert (-1,-1) to the symbolic '-1+i*(-1)' and ->num to convert that back to (-1,-1), or actually, (-1.,-1.).
Bottom line, if you're going to be nitpicky about the form of the result, you'll have to do a little more work on it.
You can get the result you expect if you first enter (-1,-1) and then do ARG. You'll get a numeric which you can convert to the desired symbolic with an XQ or a ->Q(pi) operation.
You also can use XQ to convert (-1,-1) to the symbolic '-1+i*(-1)' and ->num to convert that back to (-1,-1), or actually, (-1.,-1.).
Bottom line, if you're going to be nitpicky about the form of the result, you'll have to do a little more work on it.
--- On Wed, 10/22/08, Simone <gems_tux@...> wrote:
> From: Simone <gems_tux@...>
> Subject: [50g] principal value of ARG(z) of a complex number z
> To: 50g@yahoogroups.com
> Date: Wednesday, October 22, 2008, 2:33 AM
> Why HP 50g uses this definition of principal value of ARG(z)
> of a
> complex number z: (ARG(z=x+y*i)->
> ATAN(y/x)+(1-x/ABS(x))*pi/2?
>
> -pi<principal value of ARG(z)<=pi ->
> http://en.wikipedia.org/wiki/Complex_number#Polar_form
>
> Ex. ARG(-1-1*i)=(5/4)*pi instead of -(3/4)*pi
>
> Greetings,
> Simone.
>
>
>
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