On 12/19/2012 07:44 PM, John Cremona wrote:
On 19 December 2012 10:49, Charles Bouillaguet
<charles.bouillag...@gmail.com> wrote:
On Dec 19, 2012, at 4:16 AM, P Purkayastha wrote:
On 12/19/2012 12:28 AM, Charles Bouillaguet wrote:
Hi all,
There seems to be an inconsistency between the docstrings and the actual
behavior of some module-related methods. For instance, I am surprised by the
behavior of the coordinates() method :
It is consistent with whatever A.ambient_vector_space() is doing. There is even
a doctest:
sage: M = ZZ^3;
sage: V = M.ambient_vector_space(); V
Vector space of dimension 3 over Rational Field
Since the "ambient vector space" is the Rational field, A.coordinates returns the
rational numbers. I don't know what is meant by the term "ambient vector space" in this
context.
Fair enough, but the docstring of A.coordinates() says nothing about ambient
space. So I think that a) either the docstring must be fixed or b) the function
must be fixed.
Which one has your preference ?
I suggest adding to the documentation of A.coordinates() that it works
also if the given element is in the ambient space, with an example of
that. In concrete terms you need the element to be an F-linear
combination of the generators where F is the fraction field of the
base ring R, and not just an R-linear combination.
This functionality is useful (I have used it in some number field
functions) and I would not want it removed.
John
Well, the docstring is incorrect. I guess that was what the "check=True"
argument was for - to allow the ambient space. The "check=True" argument
is specious since no checks are actually made.
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