Remove src/sage/symbolic/todo.txt

[slelievre]

Turn any remaining items of the todo list in that file into tickets.

[gh-DaveWitteMorris]

Here are (all but one of) the issues that are not marked "done" in the file. I am numbering them, for ease of reference.

Todo 1: genuine coercions to real field, etc.

Todo 2: optimize is_even in numeric.cpp

Todo 3: Support pickle via the "archive" print mode.

Todo 4: need to be able to do this (from ginsh):
> collect_common_factors(x/(x^2 + x));
(1+x)^(-1)

Todo 5: Maybe change Sage's GiNaC to make a call to a Cython gcd function, then use
Singular, since Singular's gcd over QQ is much better than GiNaC's, I think,
and GiNaC *only* does GCD over QQ.  Actually, just make everything in normal.cpp
be implemented via Singular, probably...

If there is no discussion, I will open a single that lists all 5 of these.

[gh-DaveWitteMorris]

Here is the one issue that is missing from the above list:

* print degree order:
Now,
sage: x^2 + x^4 + x^3
x^2 + x^3 + x^4
sage: a^3*x^10 + x^12 - a^15
x^12 + a^3*x^10 - a^15

So it is printing from lowest to highest degree, like mathematica (or power series),
but unlike the standard sage convention (or maple, singular, MATH, etc.):
sage: R.<a,x> = QQ[]
sage: a^3*x^10 + x^12 - a^15
-a^15 + a^3*x^10 + x^12
sage: singular(a^3*x^10 + x^12 - a^15)
-a^15+a^3*x^10+x^12

I did not include it because this issue is also done, even though it was not marked that way in the file. With 9.3b6, we have:

sage: var("a");                                                                        
sage: x^2 + x^4 + x^3                                                                  
x^4 + x^3 + x^2
sage: a^3*x^10 + x^12 - a^15                                                           
-a^15 + a^3*x^10 + x^12

The terms go from highest degree to lowest, as they should.

[gh-DaveWitteMorris]

PR removes the todo file.

---

New commits:

​cf120a8

trac 30482 emove todo.txt

[gh-DaveWitteMorris]

The tasks listed in comment:2 are now in #31393.

[slelievre]

The commit message has a typo ("emove" for "remove"); amend it and force push?

[gh-DaveWitteMorris]

I'm not confident enough with git to try a force push. It's fine with me if you want to do that (the branch is public), or I could push a new branch with the correct commit message.