Plotting Using Trapezodial Rule-CodePudding

So I am trying to plot f = cos(x) using the trapezoidal rule but I keep getting an error saying:

TypeError: only length-1 arrays can be converted to Python scalars

I am not sure how the function is spitting out an array and not values.

import numpy as np
import matplotlib.pyplot as plt
import math as math



f = lambda x : math.cosh(4*x)
a = 0
b = 5
N = 8

# x and y values for the trapezoid rule
x = np.linspace(a,b,N 1)
y = f(x)

# X and Y values for plotting y=f(x)
X = np.linspace(a,b,100)
Y = f(X)
plt.plot(X,Y)

for i in range(N):
    xs = [x[i],x[i],x[i 1],x[i 1]]
    ys = [0,f(x[i]),f(x[i 1]),0]
    plt.fill(xs,ys,'b',edgecolor='b',alpha=0.2)

plt.title('Trapezoid Rule, N = {}'.format(N))
plt.show()

CodePudding user response：

No need to mix frameworks, use:

f = lambda x : np.cosh(4*x)

CodePudding user response：

import numpy as np
import matplotlib.pyplot as plt
import math as math



f = lambda x : math.cosh(4*x)
a = 0
b = 5
N = 8

# x and y values for the trapezoid rule
x = np.linspace(a,b,N 1)
y = [f(i) for i in x]  # this is a change

# X and Y values for plotting y=f(x)
X = np.linspace(a,b,100)
Y = [f(j) for j in X]  #this is a change
plt.plot(X,Y)

for i in range(N):
    xs = [x[i],x[i],x[i 1],x[i 1]]
    ys = [0,f(x[i]),f(x[i 1]),0]
    plt.fill(xs,ys,'b',edgecolor='b',alpha=0.2)

plt.title('Trapezoid Rule, N = {}'.format(N))
plt.show()

I have commented the changes.