Does anybody mind clarifying what the three argument signum means?

I have the expression

signum(0,R-sqrt(R^2+z^2),1)

in which z>0, R>0. I guess I know what signum means, however in this case according to the help it is considering signum of 0 and then in the help it is talking about some environment variable. I just dont quite understand...

Does it mean Maple has issues to clarify the sign of R-sqrt(R^2+z^2) ??

Thanks

How do I convert a complex number to abs and arg presentation.

For example:

z=1+1*I would be z=sqrt(2)*exp(I*Pi/4)

or when doing a calculation how can I tell him to always present these number in that form and do not expand out.

Thanks

Why does

MultiSeries:-series(LegendreQ(-1/2,x),x=-1))

not work?

series(LegendreQ(-1/2,x),x=-1))

seems to work, but does it give the correct result?

I actually thought there was a pole at -1.

Thx

PS: or is the cut between -1 and 1 with both logarithmic singularities?

I'm still wondering about the behaviour of MultiSeries

When I have an Operator like

eq:=1/r*diff(r*diff(f(r),r),r)

typically maple evaluates/expands it by product rule.

How can I tell him to not do it?

I tried using the inert operator % but probably i didn't do it right.

Probably I'm doing something severely wrong, but

sum(x^n,n=0..infinity)

does not evaluate to the geometric series result 1/(1-x), why?

Similarly this happens for the sum(x^n/n,n=1..infinity)

It works with Maple17 though.