How do I implement the sigmoid function in Octave?

Question

so given that the sigmoid function is defined as hθ(x) = g(θ^(T)x), how can I implement this funcion in Octave given that g = zeros(size(z)) ?

score 11 · Accepted Answer · answered Dec 19 '17 at 17:00

11

This will compute the sigmoid of a scalar, vector or matrix.

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


% Compute the sigmoid of each value of z (z can be a matrix,
% vector or scalar).

SIGMOID = @(z) 1./(1 + exp(-z));

g = SIGMOID(z);

end

answered Dec 19 '17 at 17:00

gingermander

573
3
11

Was using '/' in place of './'. My very very bad. – Yogesh Sanchihar Jun 17 '18 at 07:26
8

You could just use `g = 1 ./ (1 + exp(-z));` instead of creating this `SIGMOID` inside the `sigmoid` function. – Alisson Reinaldo Silva Oct 11 '18 at 03:01
`g= 1./ (1 + exp(-z));` careful about ./ divide had (dot sign) & parentheses of (1 + ...) is mandatory here, I spend mins debugging that. – Aung Zan Baw May 28 '21 at 13:27

How do I implement the sigmoid function in Octave?

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