Machine learning: gradient descent method

import numpy as np
import tensorflow as tf
from matplotlib import pyplot as plt
x = tf.linspace(-10.0, 10.0, 100)
x=tf.Variable(x)# During the calculation x It needs to be transformed into a change tensor 
with tf.GradientTape() as tape: # Tracking gradient 
    s=1/(1+tf.math.exp(-x))
grad=tape.gradient(s,x) # Calculate the gradient 
grad
plt.plot(x.numpy(),grad.numpy()) #x.numpy() Represents an array