Hi John and Jason, thanks -- the inject_variables() did what I
want.
I have another question below and hope you can help
what if I already have create a function call f = x - y as below
sage: vs = var('x y')
sage: f = x - y
sage: type(f)
<type 'sage.symbolic.expression.Expression'>
now I want to convert f to
sage.rings.polynomial.multi_polynomial_element.MPolynomial_polydict ,
is there any convenient way to do so ? One way is to define
variables x,y in PolynomialRing QQ and then redefine f = x-y but it's
quite inconvenient.
sage: vs = var('x y')
sage: R = PolynomialRing(QQ,vs)
sage: R.inject_variables()
Defining x, y
sage: f = x -y
sage: type(f)
<type
'sage.rings.polynomial.multi_polynomial_libsingular.MPolynomial_libsingular'>
sage: type(x)
Thanks again for the quick helps
On Sep 7, 12:03 pm, Jason Grout <[email protected]> wrote:
> On 9/7/10 12:47 PM, tvn wrote:
>
> > Hi, given a list of variable names as strings (e.g., l =
> > ['a','b','c','d']) I try to make those become variables in a
> > Polynomial Ring. One way is to do something like
> > R.<a,b,c,d>=CC['a','b','c','d'] , after this the type of a or b or c
> > or d is<class
> > 'sage.rings.polynomial.multi_polynomial_element.MPolynomial_polydict'> .
>
> > How can I do this in a more automatic way that can take in the list l
> > and do the same thing as above (e.g., make a,b,c,d of type<class
> > 'sage.rings.polynomial.multi_polynomial_element.MPolynomial_polydict'>)
> > without having to manually type R.<a,b,c,d> ?
>
> > Thanks in advance
>
> Something like this?
>
> sage: R=CC[','.join('x{0}'.format(i) for i in range(20))]
> sage: R.inject_variables()
> Defining x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13,
> x14, x15, x16, x17, x18, x19
> sage: type(x0)
> <class
> 'sage.rings.polynomial.multi_polynomial_element.MPolynomial_polydict'>
>
> Jason
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