normalise.m

VARHMMBOX, version 1.1, Iead Rezek, Oxford University, MAR 2002 Matlab toolbox for Hidden Markov Mo

function [ndata,refval] = normalise(data,type,val)
% [ndata,refval] = normalise(data,type,val)
%
%NORMALISE Normalises a data sequence. 
%       Normalisation type maybe with respect to 
%       variance/sd     if type is set to 's' ; makes std(data)=1
%       or amplitude    if type is set to 'a' ; makes 0<= data <=1 
%
% and with respect to a particular value



if size(data,2)>size(data,1),
   data=data';
end;

if (nargin<2) 
  type='a'; 
end;

if (type=='s')
  if ~exist('val','var'),
    refval=std(data);
  else
    refval=val;
  end
  data=detrend(data,'constant');
  ndata=data./refval(ones(size(data,1),1),:);
else
  data=detrend(data,0);
  amin=abs(min(data));
  data=amin(ones(size(data,1),1),:)+data;
  if ~exist('val','var'),
    refval=1;
  else
    refval=val;
  end
  amax=max(data);
  ndata=data./amax(ones(size(data,1),1),:)*refval;
end;