TypeError：--不支持的操作数类型-用于绘制程序的'int'和'list'

Question

I am getting the following error for the code below in line 11(where b is defined):

unsupported operand type(s) for -: 'int' and 'list'

#Needed libraries
import numpy as np
import matplotlib.pyplot as mpl

#Defining given complex refractive indices 
N1=complex(1.5,-7.6)
N2=complex(1.0,0.0)

#Defining the function that gives physically reasonable answer for effective medium
def B(x):
    a=-2
    b=(N1**2)*(2*(1-x)-x)+(N2**2)*(2*x-(1-x))
    c=(N1**2)*(N2**2)
    Nsq = (-b + np.sqrt(b**2-4*a*c))/(2*a)
    return np.sqrt(Nsq)

#Plotting the function
G=B(n)
mpl.plot(n,G)
mpl.show()

Could someone help me out? I'm not sure where the problem is and I'm not too experienced with scientific python usage. Thanks!

Answer 1

Fixed your code to:

• define a range of floats between 0 and 1
• call B on each value and compose an array

code:

#Needed libraries
import numpy as np
import matplotlib.pyplot as mpl

#Defining given complex refractive indices
N1=complex(1.5,-7.6)
N2=complex(1.0,0.0)

#Defining the function that gives physically reasonable answer for effective medium
def B(x):
    a=-2
    b=(N1**2)*(2*(1-x)-x)+(N2**2)*(2*x-(1-x))
    c=(N1**2)*(N2**2)
    Nsq = (-b + np.sqrt(b**2-4*a*c))/(2*a)
    return np.sqrt(Nsq)

nb_values = 10  # you can set it higher
n = np.linspace(0,1,nb_values+1)
# returns array([ 0. ,  0.1,  0.2,  0.3,  0.4,  0.5,  0.6,  0.7,  0.8,  0.9,  1. ])

#calling the function for each x in n, build an array from results
G=[B(x) for x in n]
#Plotting the function
mpl.plot(n,G)
mpl.show()