Steepest descent method using theano.scan()

theano_scan_steepest_descent_method.py

import theano
import theano.tensor as T

# Steepest descent method using theano.scan()

def fn(x, learning_rate):
    y = x ** 2 - x
    return x - learning_rate * T.grad(y, x)

init_x = T.dscalar()
result, updates = theano.scan(fn=fn,
                              outputs_info=init_x,
                              non_sequences=0.3,
                              n_steps=100)
f2 = theano.function([init_x], result[-1], updates=updates)

print(f2(1))  # 0.5