[Maxima] Ordering of vector variables?

[Raymond Toy (RT/EUS)]

Robert Dodier wrote:
> On Mon, Mar 24, 2008 at 9:45 AM, Raymond Toy (RT/EUS)
> <raymond.toy at ericsson.com> wrote:
> 
>> While playing with donlp2, I noticed that maxima orders vector variables
>>  in "reverse" order.   For example,
>>
>>  sum(x[k],k,1,5) -> x[5]+x[4]+x[3]+x[2]+x[1].
>>
>>  While I usually just accept whatever order maxima wants to display
>>  variables, this particular example seems wrong.  There's a natural
>>  ordering and it's by the index of the variable.
>>
>>  Any reason why it should be in reverse order?  Any objections to
>>  changing it for this case?  (I don't know if that's really possible or
>>  not.  I haven't looked.)
> 
> The terms x[1], x[2], ... are stored in order of increasing index.
> Whether they are displayed that way or reversed is controlled
> by the global variable powerdisp. When powerdisp=true the terms
> are displayed in order of increasing index.

So many globals!  powerdisp certainly does what I want, but it also 
changes how polynomials are displayed.  I always want vectors displayed 
in increasing order of index, but polynomials are different.

But this works for me.  No need to change the default.

> 
> I'm not opposed to changing the default value of powerdisp to true.
> 
> Aside from changing powerdisp, we could also change GREAT
> (the function which implements Maxima's idea of canonical
> ordering). Changing GREAT could have rippling effects, though.

If I were to make such a change, I would have it only affect arrays, and 
maybe only 1D arrays.  That should limit the effects.

But powerdisp suits me for now.

Thanks,

Ray