Please replace g=1/(m+exp(-z));
with g=1./(m+exp(-z));
in your method sigmoid
z = [2,3,4;5,6,7] ;
%SIGMOID Compute sigmoid functoon
% J = SIGMOID(z) computes the sigmoid of z.
% You need to return the following variables correctly
g=zeros(size(z));
m=ones(size(z));
% ====================== YOUR CODE HERE ======================
% Instructions: Compute the sigmoid of each value of z (z can be a matrix,
% vector or scalar).
g=1./(m+exp(-z));