title: How is Hard Sigmoid defined
body: <p>I am working on Deep Nets using keras. There is an activation "hard sigmoid". Whats its mathematical definition ?</p>
  
  <p>I know what is Sigmoid. Someone asked similar question on Quora: <a href="https://www.quora.com/What-is-hard-sigmoid-in-artificial-neural-networks-Why-is-it-faster-than-standard-sigmoid-Are-there-any-disadvantages-over-the-standard-sigmoid" rel="noreferrer">https://www.quora.com/What-is-hard-sigmoid-in-artificial-neural-networks-Why-is-it-faster-than-standard-sigmoid-Are-there-any-disadvantages-over-the-standard-sigmoid</a></p>
  
  <p>But I could not find the precise mathematical definition anywhere ?</p>