title: Tensorflow: NameError: name 'x_train' is not defined
body: <p>I'm new into tensorflow. I'm receiving this error...</p>
  
  <blockquote>
    <p>Traceback (most recent call last):
    File "C:\Users\s\Desktop\linear.py", line 36, in 
    sess.run(train, {x: x_train, y: y_train})
    NameError: name 'x_train' is not defined</p>
  </blockquote>
  
  <p>My Code:</p>
  
  <pre><code>import tensorflow as tf
  
  # y = mx + b
  
  #Model input and output
  x = tf.placeholder(tf.float32)
  y = tf.placeholder(tf.float32)
  
  # Model parameter
  m = tf.Variable([.3], tf.float32)
  b = tf.Variable([-.3], tf.float32)
  
  linear_model = m * x + b
  
  # Loss function
  loss = tf.reduce_sum(tf.square(linear_model - y))
  
  #optimizer
  optimizer = tf.train.GradientDescentOptimizer(0.01)
  train = optimizer.minimize(loss)
  
  #training data 
  x_data = [1,2,3,4]
  y_data = [0,-1,-2,-3]
  
  # Run session
  sess = tf.Session()
  init = tf.global_variables_initializer()
  sess.run(init)
  
  #tTensorboard
  writer = tf.summary.FileWriter('./graphs', sess.graph)
  
  # highest value for range is 25,000
  for i in range(1000):
      sess.run(train, {x: x_train, y: y_train})
      # evaluation
      curr_m, curr_b, curr_loss = sess.run([m,b,loss], {x: x_train, y: y_train})
      # print 
      print("%s, %s, %s"%(curr_m, curr_b, curr_loss))
  
  writer.close()
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/iifIu.png" rel="nofollow noreferrer">This is the screenshot</a></p>