On 05/18/2010 11:14 AM, John Cremona wrote:
In our example, how does DifferentialForms() know that there are three
variables?
Also, note that the syntax F.<x,y,z> = ... would normally be a
shorthand for something like F = ....; x,y,z = F.gens().
Good point. Joris, the <x,y,z> syntax is just syntactic sugar that is
preparsed into:
sage: preparse('F.<x,y,z>=DifferentialForms()')
"F = DifferentialForms(names=('x', 'y', 'z',)); (x, y, z,) =
F._first_ngens(3)"
So you can see from the "(x,y,z,)=..." statement that you are in reality
defining the variables "x", "y", and "z", and there is nothing a class
can do about that without changing the preparser.
In fact, if I wanted to call what you call "dx" by the name "x", I
suppose that is my business, regardless of how many conventions it
messes up :).
In that sense, would it be so hard to expect the user to do something like:
F.<dx,dy,dz>=DifferentialForms()
which preparses into
sage: preparse('F.<dx,dy,dz>=DifferentialForms()')
"F = DifferentialForms(names=('dx', 'dy', 'dz',)); (dx, dy, dz,) =
F._first_ngens(3)"
Thanks,
Jason
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