TypeError:无法将表达式转换为浮点型 [英] TypeError: can't convert expression to float
问题描述
我是python新手.我正在尝试使用python评估Planck方程.我写了一个简单的程序.但是,当我输入信息时,会给我一个错误.谁能帮助我解决我的问题?这是程序和错误:
I am a python newbie. I am trying to evaluate Planck equation using python. I have written a simple program. But when I give input to it is giving me an error. can anyone hep me where I am going wrong? Here is the program and the error:
程序:
from __future__ import division
from sympy.physics.units import *
from math import *
import numpy
from scipy.interpolate import interp1d
#Planck's Law evaluation at a single wavelength and temperature
def planck_law(wavelength,temperature):
T=temperature
f=c/wavelength
h=planck
k=boltzmann
U=2*h/(c**3)*(f**3)/(exp(h*f/(k*T))-1)
return U.evalf()
输入: 我已将功能导入为"cp",输入如下:
Input: I have imported the function as 'cp' and the input is as follows
value = (cp.planck_law(400,2000))
错误:
Traceback (most recent call last):
File "<stdin>", line 1, in <module>`enter code here`
File "Camera_performance.py", line 14, in planck_law
U=2*h/(c**3)*(f**3)/(exp(h*f/(k*T))-1)
File "/usr/lib/python2.7/dist-packages/sympy/core/expr.py", line 221, in __float__
raise TypeError("can't convert expression to float")
TypeError: can't convert expression to float
推荐答案
您似乎正在混合名称空间,因为您正在使用from ... import *
.您想使用sympy.exp()
,但是您的代码使用math.exp()
.良好的做法是将名称空间保持分隔,即从不使用from ... import *
-乍一看似乎要键入更多内容,但最终会产生更清晰,更容易理解的代码.
试试:
It seem like you are mixing namespaces, since your are using from ... import *
. You wanted to use sympy.exp()
but your code uses math.exp()
. It is good practice to keep the namespaces separated, i.e. never use from ... import *
- it might seem like more typing at first, but will produce much cleaner easier comprehensible code in the end.
Try:
import sympy as sy
import sympy.physics.units as units
def planck_law(wavelength,temperature):
"""Planck's Law evaluation at a single wavelength and temperature """
T=temperature
f=units.c/wavelength
h=units.planck
k=units.boltzmann
U=2*h/(units.c**3)*(f**3)/(sy.exp(h*f/(k*T))-1)
return U.evalf()
# Test:
print(planck_law(640e-9*units.m, 500*units.K))
# Result: 1.503553603007e-34*kg/(m*s)
这篇关于TypeError:无法将表达式转换为浮点型的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!