tensorflow 求函数极值

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求函数f(x,y)=x^2+y^2的极小值

import tensorflow as tf
from tensorflow.python.framework import ops
ops.reset_default_graph()
sess=tf.Session()
x=tf.Variable(tf.constant(4.))
y=tf.Variable(tf.constant(3.))
a_val=1
a_data=tf.placeholder(dtype=tf.float32)
multiplication=x*x*a_data+y*y*a_data

loss = multiplication ##loss函数就是函数本身

# Initialize variables
init = tf.global_variables_initializer()
sess.run(init)

# Declare optimizer
my_opt = tf.train.GradientDescentOptimizer(0.01)
train_step = my_opt.minimize(loss)

# Run loop across gate
print('Optimizing a Multiplication Gate Output to 50.')
for i in range(1000):
    sess.run(train_step, feed_dict={a_data: a_val})
    x_val = sess.run(x)
    y_val=sess.run(y)
    mult_output = sess.run(multiplication, feed_dict={a_data: a_val})
    print('x_val:'+str(x_val)+',y_val:'+str(y_val) +'=f(x,y):' + str(mult_output))


x_val:1.1383e-08,y_val:8.53728e-09=f(x,y):2.02458e-16
x_val:1.11554e-08,y_val:8.36653e-09=f(x,y):1.94441e-16
x_val:1.09322e-08,y_val:8.1992e-09=f(x,y):1.86741e-16
x_val:1.07136e-08,y_val:8.03522e-09=f(x,y):1.79346e-16
x_val:1.04993e-08,y_val:7.87451e-09=f(x,y):1.72244e-16
x_val:1.02893e-08,y_val:7.71702e-09=f(x,y):1.65423e-16
x_val:1.00836e-08,y_val:7.56268e-09=f(x,y):1.58872e-16
x_val:9.88189e-09,y_val:7.41143e-09=f(x,y):1.52581e-16
x_val:9.68425e-09,y_val:7.2632e-09=f(x,y):1.46539e-16
x_val:9.49056e-09,y_val:7.11794e-09=f(x,y):1.40736e-16
x_val:9.30075e-09,y_val:6.97558e-09=f(x,y):1.35163e-16
x_val:9.11474e-09,y_val:6.83607e-09=f(x,y):1.2981e-16
x_val:8.93244e-09,y_val:6.69934e-09=f(x,y):1.2467e-16
x_val:8.75379e-09,y_val:6.56536e-09=f(x,y):1.19733e-16
x_val:8.57872e-09,y_val:6.43405e-09=f(x,y):1.14991e-16
x_val:8.40714e-09,y_val:6.30537e-09=f(x,y):1.10438e-16
x_val:8.239e-09,y_val:6.17926e-09=f(x,y):1.06064e-16
x_val:8.07422e-09,y_val:6.05568e-09=f(x,y):1.01864e-16
x_val:7.91274e-09,y_val:5.93456e-09=f(x,y):9.78304e-17
x_val:7.75448e-09,y_val:5.81587e-09=f(x,y):9.39563e-17
x_val:7.59939e-09,y_val:5.69955e-09=f(x,y):9.02357e-17
x_val:7.4474e-09,y_val:5.58556e-09=f(x,y):8.66623e-17
x_val:7.29846e-09,y_val:5.47385e-09=f(x,y):8.32305e-17
x_val:7.15249e-09,y_val:5.36437e-09=f(x,y):7.99346e-17
x_val:7.00944e-09,y_val:5.25709e-09=f(x,y):7.67692e-17
x_val:6.86925e-09,y_val:5.15195e-09=f(x,y):7.37291e-17
x_val:6.73186e-09,y_val:5.04891e-09=f(x,y):7.08095e-17

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关键词：极小值