In Python, I want to use the hypergeometric function hyp2f1 while keeping at least one symbolic argument. However, there is a TypeError
cannot create mpf from d
where d is the (last) argument of the hypergeometric function.
Someone asked a similar question
sympy and mpmath give "TypeError: cannot create mpf" when using the erf() function within solveset()
after encountering the same problem with the error function erf. The proposed solution was to use the mpmath library instead of the sympy library, but mpmath cannot be used while keeping arguments symbolic.
I also tried to import mpmath and sympy together as proposed in the sympy documentation:
from sympy.mpmath import *
But this is not accepted, as the output is:
ModuleNotFoundError: No module named `sympy.mpmath'
My code is
from sympy import *
d = Symbol('d')
hyp2f1(1,1,1,d)
I hoped to get a simplification to 1/(1-d) or at least hoped that Python can 'store' hyp2f1(1,1,1,d) for symbolic manipulations.
I get an error
TypeError: cannot create mpf from d
The bottom line is, with sympy imported, Python cannot use hyp2f1 with symbolic arguments.
Use the SymPy hyper function:
In [4]: from sympy import hyper, simplify, Symbol
In [5]: d = Symbol('d')
In [6]: f = hyper([1, 1], [1], d)
In [7]: f
Out[7]:
┌─ ⎛1, 1 │ ⎞
├─ ⎜ │ d⎟
2╵ 1 ⎝ 1 │ ⎠
In [8]: simplify(f)
Out[8]:
1
─────
1 - d