Question

Write a function called polyplot that has one input array with three elements and no outputs. The array elements A, B, and C are coefficients of a polynomial equation y=Ax^3+Bx^2+Cx. The function should plot the equation with a red line and blue x's for markers. There should be 20 values of x varying from -5 to 5. The plot title is "Plot of y=Ax^3+Bx^2+Cx" where the characters A, B, and C are replaced with the actual values from the function input.

Answer 1

Here is the function as per the requirement, I have explained everything in code. We created a function that takes an array as the argument. I have used matplotlib in python to generate the plot.

here is the output

here is text code:

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import numpy as np
import matplotlib.pyplot as plt

#here is the function, it accepts 3 arguments
def polyplot(arr):
   A=arr[0]
   B=arr[1]
   C=arr[2]
   x = [-5.0]
   y = [ A*x[0]**3 + B*x[0]**2 + C*x[0] ]
   #this loop generates values corresponding to given formula using A,B and C
   for i in range(1,20):
       x.append(x[i-1]+0.5)
       y.append(A*x[i]**3 + B*x[i]**2 + C*x[i])
   #plot red line
   plt.plot(x, y, '-r')
   #plot red x marker
   plt.plot(x, y, 'xb')
   #title
   T = 'plot of '+str(A)+'x^3 + '+str(B)+'x^2 +'+str(C)+'x'
   plt.title(T)
   #show plot
   plt.show()

#dummy values of A, B and C used to text function
arr = [4,3,2]
arr = np.array(arr)
polyplot(arr)

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