# [Maxima] symbol evaluation order

Barton Willis willisb at unk.edu
Tue May 22 08:21:07 CDT 2007

```Try ev(V,infeval). Maxima's evaluation scheme might be described as one
ply.
But it's not always one ply! Look at this:

(%i1) (a : b, b : c, c : d)\$
(%i2) a;
(%o2) b      <-- one ply evaluation

(%i3) a[1];
(%o3) d[1]   <-- why not b[1] ?

Barton

-----maxima-bounces at math.utexas.edu wrote: -----

>To: maxima at math.utexas.edu
>From: "Brian W."
>Sent by: maxima-bounces at math.utexas.edu
>Date: 05/22/2007 08:01AM
>Subject: [Maxima] symbol evaluation order
>
>Hello,
>I am a maxima beginner, and I don't quite understand how expressions are
>evaluated. In the example session below (calculating the volumen V of a
>sphere with radius r, diameter d), the final evaluation ''V results in an
>expression containing d, although d is defined.
>
>What should I have typed, so that the value of d is substituted in the
>evaluation? Of course I could write ''V,d=d; but I would like to have all
>known symbols substituded recursively (for more complicated examples).
>
>Thanks
>Brian
>
>(%i1) V:4/3*%pi*r^3;
>                                          3
>                                   4 %pi r
>(%o1)                              --------
>                                      3
>(%i2) r:d/2;
>                                       d
>(%o2)                                  -
>                                       2
>(%i3) d:20;
>(%o3)                                 20
>(%i4) ''V;
>                                         3
>                                    %pi d
>(%o4)                               ------
>                                      6
>(%i5)
>--
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>http://www.nabble.com/symbol-evaluation-order-tf3796196.html#a10737392
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```