simplification of atan2(0,x)



Ah, of course, thanks!


On Sunday, February 03, 2013 10:07:11 pm Stavros Macrakis wrote:
> atan2(0,x) is 0 for x>0, %pi for x<0, and undefined for x=0.
> 
> If you'd like Maxima to simplify atan2(0,x), you need to tell it what the
> sign of x is.
> 
> For example:
> 
> (%i1) assume(x>0);
> (%o1)                               [x > 0]
> (%i2) atan2(0,x);
> (%o2)                                  0
> (%i3) atan2(0,-x);
> (%o3)                                 %pi
> 
> Hope this helps.
> 
>                -s
> 
> On Sun, Feb 3, 2013 at 3:46 PM, Nijso Beishuizen <nijso at hotmail.com> wrote:
> > Dear all,
> > 
> > I sometimes get as an intermediate solution of a calculation atan2(0,x).
> > 
> > When x:5, then trigreduce knows that atan2(0,5) = 0, but when x is
> > defined as
> > a constant or nothing is assumed on x, then atan2 stays.
> > 
> > I don't speak lisp, but I think the simplification atan2(0,x)=0 can be
> > done by
> > adding something in comm2.lisp?
> > 
> > Best,
> > NB
> > 
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