logsig
Log-sigmoid transfer function
Graph and Symbol
Syntax
A = logsig(N,FP)
dA_dN = logsig('dn',N,A,FP)
info = logsig('code')
Description
logsig is a transfer function. Transfer functions calculate a layer’s
output from its net input.
A = logsig(N,FP) takes N and optional function
parameters,
N |
|
FP | Struct of function parameters (ignored) |
and returns A, the S-by-Q matrix
of N’s elements squashed into [0, 1].
dA_dN = logsig('dn',N,A,FP) returns the
S-by-Q derivative of A with respect to
N. If A or FP is not supplied or is
set to [], FP reverts to the default parameters, and
A is calculated from N.
info = logsig(' returns useful
information for each code')code character vector:
logsig('name') returns the name of this function.
logsig('output',FP) returns the [min max] output
range.
logsig('active',FP) returns the [min max] active
input range.
logsig('fullderiv') returns 1 or 0, depending on whether
dA_dN is
S-by-S-by-Q or
S-by-Q.
logsig('fpnames') returns the names of the function parameters.
logsig('fpdefaults') returns the default function parameters.
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)
Assign this transfer function to layer i of a network.
net.layers{i}.transferFcn = 'logsig';
Algorithms
logsig(n) = 1 / (1 + exp(-n))