Neural Network Toolbox

logsig

Log sigmoid transfer function

Graph and Symbol

Syntax

A = logsig(N)

info = logsig(code)

Description

logsig is a transfer function. Transfer functions calculate a layer's output from its net input.

logsig(N) takes one input,

• N - S x Q matrix of net input (column) vectors.

and returns each element of N squashed between 0 and 1.

logsig(code) returns useful information for each code string:

• 'deriv' - Name of derivative function.

  'name' - Full name.

  'output' - Output range.

  'active' - Active input range.

Examples

Here is the code to create a plot of the logsig transfer function.

• n = -5:0.1:5;
  a = logsig(n);
  plot(n,a)
  

Network Use

You can create a standard network that uses logsig by calling newff or newcf.

To change a network so a layer uses logsig, set net.layers{i}.transferFcn to 'logsig'.

In either case, call sim to simulate the network with purelin.

See newff or newcf for simulation examples.

Algorithm

logsig(n) = 1 / (1 + exp(-n))

See Also

• sim, dlogsig, tansig
  

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