[Maxima] strange behaviour with simple decimals

[Andrey G. Grozin]

I'd like to stress one general point about maxima (or any other CAS). 
maxima *always* transforms its input to its internal representation. It is 
*not* a passive "paper" on which you can write some expression and expect 
it to stay in the form you have written. This is in no way restricted to 
numbers.

(%i1) a:x-y$
(%i2) part(a,0); part(a,2); part(a,2,0);
(%o2)                                  +
(%o3)                                 - y
(%o4)                                  -

This shows that when you write x-y, maxima immediately transforms this to 
its internal representation x+(-y).

(%i5) a:x^(1/2);
(%o5)                               sqrt(x)
(%i6) part(a,0);
(%o6)                                sqrt

The power 1/2 is transformed to sqrt.

And so on. Such examples are innumerable. So, the expectation that maxima 
(or any other CAS) will work with the expression you input is wrong. It 
will always transform it into its internal representation, and work with 
it.

Andrey