深度学习的始祖框架，grandfather级别的框架 —— Theano —— 示例代码学习（5）

代码1：（求雅可比矩阵， jacobian矩阵求解）

import theano
from theano import tensor

# Creating a vector
x = tensor.dvector('x')

# Creating 'y' expression
y = (2 * x ** 3)

# Computing derivative
Output, updates = theano.scan(lambda i, y, x : tensor.grad(y[i], x),\
                               sequences=tensor.arange(y.shape[0]),\
                                  non_sequences=[y, x])

# Creating function
# fun = theano.function([x], Output, updates=updates)
fun = theano.function([x], Output)

# Calling function
print( fun([3,3]) )

运行结果：

代码2：（求黑森矩阵， Hession矩阵求解）

import theano
from theano import tensor

# Creating a vector
x = tensor.dvector('x')

# Creating 'y' expression
y = (2 * x ** 3)

# Calculating cost
cost = y.sum()

# Computing derivative
derivative = tensor.grad(cost, x)
output, updates = theano.scan(lambda i, derivative,x : \
                              tensor.grad(derivative[i], x),\
                               sequences=tensor.arange(derivative.shape[0]),\
                                 non_sequences=[derivative, x])

# Creating function
# fun = theano.function([x], output, updates=updates)
fun = theano.function([x], output)

# Calling function
print( fun([3,3]) )

运行结果：