string comparisons, was: Maxima 5.21.1 release

Sometimes it helps to compare to other languages, e.g. Common Lisp.

There are functions string=, string>, string>=   etc.


they require that each of the arguments be strings. We can use these 
functions directly
from Maxima, e.g.

?string\=("abc","def").

If you overload ">"  to apply to strings, it seems to me that you should 
require
that each of the arguments be a string.

Also, string>, etc.  returns a number,  related to the location in the 
strings where the order is established.

Comparing strings with symbols  (symbol names) may possibly make sense, 
but comparing complex numbers
(an UNORDERED field) strikes me as (mathematically) batty, even if you 
can make up something to write into
a program. There are programs that provide an order for symbolic 
expressions.  The underlying
lisp program can even be called as  ?great(a,b) .

RJF



Robert Dodier wrote:
> On 4/26/10, Stavros Macrakis <macrakis at gmail.com> wrote:
>
>   
>> As for is("x">0) giving an error, that is perfectly correct -- it is
>> meaningless to compare a string to a number.
>>     
>
> Disagreed on this point -- %i and 0 are incomparable but is(%i > 0)
>  => false, not an error. By analogy, seems like is("x" > 0) should
> likewise yield false.
>
>   
>> But in fact Maxima's comparison functions (other than = and #) don't even
>> work on strings -- probably they should.
>>     
>
> Agreed, < <= >= > should be able to compare strings.
>
> best
>
> Robert Dodier
> _______________________________________________
> Maxima mailing list
> Maxima at math.utexas.edu
> http://www.math.utexas.edu/mailman/listinfo/maxima
>