rands函数的用法

有如下程序，

clc; clear; [a,b]=rands(5,1); a b [c,d]=rands(1,5); c d

输出如下：

a =

-0.5749
0.6785
0.2576
-0.7325
-0.5857


b =

0.2144
0.2598
-0.2590
0.1503
-0.0972


c =

-0.9122 -0.9456 -0.3746 -0.9743 -0.2321


d =

0.3662

有关rands函数说明如下：

rands

Symmetric random weight/bias initialization function
Syntax
W = rands(S,PR)
M = rands(S,R)
v = rands(S);

Description

rands is a weight/bias initialization function.
rands(S,PR) takes,
S -- Number of neurons
PR -- R x 2 matrix of R input ranges
and returns an S-by-R weight matrix of random values between -1 and 1.
rands(S,R) returns an S-by-R matrix of random values. rands(S) returns an S-by-1 vector of random values.
Examples

Here three sets of random values are generated with rands. rands(4,[0 1; -2 2])
rands(4)
rands(2,3)

Network Use

To prepare the weights and the bias of layer i of a custom network to be initialized with rands Set net.initFcn to 'initlay'. (net.initParam will automatically become initlay's default parameters.) Set net.layers{i}.initFcn to 'initwb'. Set each net.inputWeights{i,j}.initFcn to 'rands'. Set each net.layerWeights{i,j}.initFcn to 'rands'. Set each net.biases{i}.initFcn to 'rands'.
To initialize the network call init

---

没有说明，如何出现上述结果，百度之：

function [w,b] = rands(s,pr)


%RANDS Symmetric random weight/bias initialization function.


%


%  Syntax


%


%    W = rands(S,PR)


%    M = rands(S,R)


%    v = rands(S);


%


%  Description


%


%    RANDS is a weight/bias initialization function.


%


%    RANDS(S,PR) takes,


%      S  - number of neurons.


%      PR - Rx2 matrix of R input ranges.


%    and returns an S-by-R weight matrix of random values between -1 and 1.


%


%    RANDS(S,R) returns an S-by-R matrix of random values.


%    RANDS(S) returns an S-by-1 vector of random values.


%


%  Examples


%


%    Here three sets of random values are generated with RANDS.


%


%      rands(4,[0 1; -2 2])


%      rands(4)


%      rands(2,3)


%


%  Network Use


%


%    To prepare the weights and the bias of layer i of a custom network


%    to be initialized with RANDS:


%    1) Set NET.initFcn to 'initlay'.


%       (NET.initParam will automatically become INITLAY's default parameters.)


%    2) Set NET.layers{i}.initFcn to 'initwb'.


%    3) Set each NET.inputWeights{i,j}.initFcn to 'rands'.


%       Set each NET.layerWeights{i,j}.initFcn to 'rands';


%       Set each NET.biases{i}.initFcn to 'rands'.


%


%    To initialize the network call INIT.


%


%  See also RANDNR, RANDNC, INITWB, INITLAY, INIT




% Mark Beale, 1-31-92


% Revised 12-15-93, MB


% Revised 11-31-97, MB


% Copyright 1992-2008 The MathWorks, Inc.


% $Revision: 1.1.6.7 $  $Date: 2008/06/20 08:04:33 $




fn = mfilename;


if (nargin < 1), error('NNET:Arguments','Not enough arguments.'); end


if ischar(s)


  switch(s)


    case 'name'


      w = 'Midpoint';


    otherwise, error('NNET:Arguments',['Unrecognized code: ''' s ''''])


  end


  return


end




if nargin == 1


  r = 1;


elseif size(pr,2) == 1


  r = pr;


else


  r = size(pr,1);


end


w = 2*rand(s,r)-1;//注意






% **[ NNT2 Support ]**


if nargout == 2


  b = 2*rand(s,1)-1; //注意