Dear Yegor,
On Nov 24, 4:27 pm, "Yegor Bryukhov" <[EMAIL PROTECTED]> wrote:
> Ideally, the end user should not be aware of the fact that s/he uses 5
> libraries.
>
> So, what's Sage's approach to this problem?
Probably other people have a more substantial answer, but let's try...
Firstly, Sage is based on an object oriented language (Python
respectively Cython).
For example, having different flavours of matrices (sparse, dense,
special implementation over GF(2), defined in various interfaces,...)
will usually not matter to the user, since the code usually relies on
the methods of the objects. Now, dense and sparse matrices have most
methods in common. So, your code would not feel any difference between
dense and sparse matrices.
Secondly, Sage has a clever "coercion model" (I don't know how much
you'll find on it in the documentation; AFAIK, it is not very old).
Other people can tell you more on it. But I think the following is a
good example.
If you have a polynomial p over ZZ and a rational number r, then
apparently p and r have nearly nothing in common, from the viewpoint
of implementation. But mathematically, of course it makes sense that p
+r is a polynomial over QQ. And the coercion model takes this into
account. So, when the user does
sage: p+r
then Sage tries to find a common parent for p and r (namely
'polynomials over QQ'), maps them to the common parent in a canonical
way, and adds them there.
Cheers
Simon
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