I would like to use mpmath.quad to evaluate an integral value of a function simplified by sympy.
Then I used the following code
from sympy import *
import mpmath as mp
r = symbols("r")
f = 4**(-r)*r*(0.115391565000863*2**r + 693.147180559945)*exp(-0.000332949677174323*2**r)
mp.quad(lambda r:f,[0,1])
but get this error message
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
<ipython-input-8-715cd610bbdb> in <module>()
3 r = symbols("r")
4 f = 4**(-r)*r*(0.115391565000863*2**r + 693.147180559945)*exp(-0.000332949677174323*2**r)
----> 5 mp.quad(lambda r:f,[0,1])
5 frames
/usr/local/lib/python3.6/dist-packages/mpmath/ctx_mp.py in _convert_fallback(ctx, x, strings)
632 else:
633 raise ValueError("can only create mpf from zero-width interval")
--> 634 raise TypeError("cannot create mpf from " + repr(x))
635
636 def mpmathify(ctx, *args, **kwargs):
TypeError: cannot create mpf from 4**(-r)*r*(0.115391565000863*2**r + 693.147180559945)*exp(-0.000332949677174323*2**r)
I tried another simple function
from sympy import *
import mpmath as mp
x = symbols("x")
f = x*2
mp.quad(lambda x:f,[1,2])
and get the same error msg too
TypeError: cannot create mpf from 2*x
Can anyone know what caused this error msg and how to use quad function correctly?
lambda r:f
does not create a callable that is what you think it is. You would have to copy and paste the definition of f
on the rhs or substitute in the function's call value:
>>> f = r + 1
>>> (lambda r:f)(1)
r + 1
>>> (lambda r: r + 1)(1)
2
>>> (lambda v:f.subs(r,v))(1)
2