标签：scala record coding usr 存储 author scalar with auth
#!/usr/bin/env python2
# -*- coding: utf-8 -*-
"""
Created on Fri Aug 10 16:13:29 2018
@author: myhaspl
"""
from mxnet import nd
from mxnet import autograd
x = nd.array([[1, 2], [3, 4]])
x.attach_grad()#在ndarray里准备存储梯度
with autograd.record():#定义f(x)
y=2*x*x
#反向传播backward()
y.backward()
#f‘(x)=4*x
z=x.grad
print x
print z
[[1. 2.]
?[3. 4.]]
<NDArray 2x2 @cpu(0)>
[[ 4. ?8.]
?[12. 16.]]
<NDArray 2x2 @cpu(0)>
######################
#!/usr/bin/env python2
# -*- coding: utf-8 -*-
"""
Created on Fri Aug 10 16:13:29 2018
@author: myhaspl
"""
from mxnet import nd
from mxnet import autograd
def f(x):
b=x
while b.norm().asscalar() < 100: #计算欧氏距离(norm)
b=b*2#y=ax ,a=2*2*.....*2
print b
if b.sum().asscalar() >= 0:
y = b[0]
else:
y = b[1]
return y
x = nd.array([1,4])
x.attach_grad()#在ndarray里准备存储梯度
with autograd.record():#定义f(x)
y=f(x)
#反向传播backward()
y.backward()
#f‘(x)=a,y=ax
z=x.grad
print "======="
print [z,x,y,y/x]#a=y/x[2. 8.]
<NDArray 2 @cpu(0)>
[ 4. 16.]
<NDArray 2 @cpu(0)>
[ 8. 32.]
<NDArray 2 @cpu(0)>
[16. 64.]
<NDArray 2 @cpu(0)>
[ 32. 128.]
<NDArray 2 @cpu(0)>
=======
[
[32. ?0.]
<NDArray 2 @cpu(0)>,?
[1. 4.]
<NDArray 2 @cpu(0)>,?
[32.]
<NDArray 1 @cpu(0)>,?
[32. ?8.]
<NDArray 2 @cpu(0)>]
标签：scala record coding usr 存储 author scalar with auth
原文地址：http://blog.51cto.com/13959448/2316718
