Theano exercise 笔记

on Others, Theano

此笔记为theano_exercises教程的记录。

该教程是大牛Ian Goodfellow写的练习题。

1. 创建一个dim维的张量，代码如下：

def make_tensor(dim):
    """
    Returns a new Theano tensor with no broadcastable dimensions.
    dim: the total number of dimensions of the tensor.
    """

    return T.TensorType(broadcastable=tuple([False] * dim), dtype='float32')()

2. 返回一个函数

def evaluate(x, y, expr, x_value, y_value):
    """
    x: A theano variable
    y: A theano variable
    expr: A theano expression involving x and y
    x_value: A numpy value
    y_value: A numpy value

    Returns the value of expr when x_value is substituted for x
    and y_value is substituted for y
    """
    f = theano.function([x, y], expr)
    return f(x_value, y_value)

简化版：

    return function([x, y], expr)(x_value, y_value)

3. Returns dz / dx + dz / dy

return T.grad(z, x) + T.grad(z, y)

简化版：

return sum(T.grad(z, [x, y]))
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