title: Keras dot/Dot layer behavior on 3D tensors
body: <p>The <a href="https://keras.io/layers/merge/" rel="noreferrer">Keras documentation for the dot/Dot layer</a> states that:</p>
  
  <p>"Layer that computes a dot product between samples in two tensors.</p>
  
  <p>E.g. if applied to a list of two tensors a and b of shape (batch_size, n), the output will be a tensor of shape  (batch_size, 1) where each entry i will be the dot product between a[i] and b[i].</p>
  
  <p>Arguments</p>
  
  <p>axes: Integer or tuple of integers, axis or axes along which to take the dot product."</p>
  
  <p>I am not getting this, here is a quick, reproducible example to demonstrate:</p>
  
  <pre><code>from keras.layers import Input, dot
  input_a = Input(batch_shape=(99,45000,300))
  input_b = Input(batch_shape=(99,45000,300))
  element_wise_dot_product = dot([input_a,input_b], axes = -1)
  print(input_a.get_shape(),input_b.get_shape(),element_wise_dot_product.get_shape()) 
  </code></pre>
  
  <p>Output: (99, 45000, 300) (99, 45000, 300) (99, 45000, 45000)</p>
  
  <p>Why is the element wise dot product shape not (99,45000,1) ? What am I doing wrong and how can i fix it?</p>