吴恩达的机器学习编程作业3：sigmoid 计算s型函数

function g = sigmoid(z)
%SIGMOID Compute sigmoid function
%   g = SIGMOID(z) computes the sigmoid of z.

% You need to return the following variables correctly 
g = zeros(size(z));

% ====================== YOUR CODE HERE ======================
% Instructions: Compute the sigmoid of each value of z (z can be a matrix,
%               vector or scalar).
denominator = 1.+exp(-z);
g = 1./denominator;




% =============================================================

end