[Maxima] infix pos use

Eligio Cerval-Peña cervale at for.mat.bham.ac.uk
Thu Oct 25 07:47:28 CDT 2007


I am trying to define the infix operator "±" but am meeting a couple of
hurdles when trying to get it to do exactly what I want.

The code I am using (in wxMaxima 0.7.2) is:
	"±"(a,b):=[a+b,a-b]$
	infix("±",79,80);

For simple numbers such as 2±3 and even 2±3*%i this works, but my problem is
that when I enter "y=a±b" I get "[y+b=b+a,y-b=a-b]", or "[(y=a)+b,(y=a)-b]"
with simp:false, whereas I want to get y=[a+b,a-b].

I don't think this is a precedence order as I have played around with the
values of these, the only thing I can think of that I haven't had any luck
with is the lpos, rpos and pos that infix can apparently take in.  I have
looked through the documentation as well as a some other online manuals but
none seem to explain what these "pos" do or how they are used.

Any advice on (1) getting the ± to work how I'd like it to, and (2) what
lpos, rpos and pos do and how to use them, very gratefully received.


Eligio



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