Help with sympy, please

[Fredrik Johansson]

On Nov 19, 2007 2:03 AM, Dick Moores <rdm at rcblue.com> wrote:
> At 04:26 PM 11/18/2007, Fredrik Johansson wrote:
> >On Nov 19, 2007 1:05 AM, Dick Moores <rdm at rcblue.com> wrote:
> >Hi Dick, I recognize you from python-list, where you had a question
> >about mpmath.
> >
> >Your code still won't work if you convert the numbers to Floats
> >because the Float type in sympy.numerics does not implement ** for
> >fractional numbers. You could use the exp function in
> >sympy.numerics.functions instead to compute e**x.
>
> Thanks, Fredrik, but I get the same error using either exp or power:
> ============================
> from __future__ import division
> from sympy import *
> from sympy import Rational as R
> from sympy.numerics import *
> from sympy.numerics.functions import power, exp
>
> prec = 50
> Float.setdps(prec)
> e = evalf(E)
> n = 1
> m = n + 1
> k = 0
> n = evalf(R(n,1))
> m = evalf(R(m,1))
> prod = evalf(R(1,1))
> prec = 50
> Float.setdps(prec)
> e = evalf(E)
> n = 1
> k = 0
> prod = evalf(R(1,1))
> while k < 1000:
>       k += 1
>       n = evalf(R(n,1))
>       term = (exp(1/n))/(exp(1/(n+1)))
>       prod *= term
>       n += 2
> print prod, term
> =============================
> term = (exp(1/n))/(exp(1/(n+1)))
> TypeError: unsupported operand type(s) for /: 'int' and 'Float'
>
> And also if I use sympy.numerics.functions.power in that line, as
> term = power(e,(1/n))/power(e,(1/(n+1)))
>
> I get:
>
> term = power(e,(1/n))/power(e,(1/(n+1)))
> TypeError: unsupported operand type(s) for /: 'int' and 'Float'

Try not using "from __future__ import division".

Also,

     n = evalf(R(n,1))

won't work, because the arguments to Rational must be ints.

Fredrik