assert_win.m

linear time－frequency toolbox

function [info,istight]=assert_win(win,dgtinfo,winname,callfun)
%ASSERT_WIN  Assert that window function is valid
%   Usage:  info=assert_win(win,dgtinfo,winname,callfun)
%
%   Input parameters:
%         win         : Representation of window, user input.
%         dgtinfo     : Info structure from assert_tt
%         winname     : name of win, e.g. 'awin' or 'swin'
%         callfun     : name of calling function.
%   Output parameters:
%         info        : Structure describing the window.
%         otherdepend : Proper calculation of window depend on the other.
%         istight     : Window is tight

% A window can be represented as a string, as a matrix or
% as a cell array.

% Does the full calculation of the window depend on the other window?
info.otherdepend=0;

% Is the window tight (i.e. replaces both windows)?
istight=0;

% Is the window a FIR window?
info.isfir=0;

% Does the window have a fixed size?
info.isfixed=0;

% Has a factorization been computed?
info.hasfac=0;

% Length of window:
%   0        - not decided yet.
%   positive - FIR window of this length
%   negative - Full window of this length
info.Lwin=0;

% Size of multiwindow
info.R=0;

% Window is represented as a string.
if ischar(win)
  win=lower(win);

  info.funpars={};

  switch win
    case {'gauss','pgauss'}
      info.funname='pgauss';
      info.funpars={[],[]};
      info.R=1;
    case {'sech','psech'}
      info.funname='psech';
      info.funpars={[],[]};
      info.R=1;
    case 'none'
    case 'phanning'
      info.isfir=1;
      info.R=1;
    case 'candual'
      info.otherdepend=1;
    case 'cantight'     
      info.otherdepend=1;
      istight=1;
    otherwise
      error([callfun,': ',win,', unknown window name'])
  end;

  info.name=win;
  info.win=win;

      
end;

% Window is represented as a cell array
if iscell(win)
  if isempty(win) || ~ischar(win{1})
    error([callfun,': ',winname,', first element must be a character string.']);
  end;
  
  npars=length(win);
  
  switch lower(win{1})
    case {'pgauss','psech'}
      switch npars
	case 1
	  win{2}=[];
	  win{3}=[];
	case 2
	  win{3}=[];
	  if ((prod(size(win{2}))>1) || ~isnumeric(win{2}))
	    error([callfun,': tfr must be a scalar or an empty matrix']);
	  end;	
	case 3
	  if  (prod(size(win{2}))>1 || ~isnumeric(win{2}))
	    error([callfun,': tfr must be a scalar or an empty matrix']);
	  end;	
	  if  (prod(size(win{3}))~=1 || ~isnumeric(win{3}))
	    error([callfun,': centering must be a scalar']);
	  end;
	  % Assert that the specified centering fits with the transform.
	  if ((win{3}==0 && dgtinfo.iseven==2) && ...
	      (win{3}==.5 && dgtinfo.iseven==1))
	    error('Specified centering of Gaussian or Sech window is in conflict with the centering allowed by the transform.');
	  end;
	otherwise
	  error('Too many input parameters for Gaussian or Sech window.');	  
      end;
      info.R=1;
    case {'pherm'}
      if npars<2
	error([callfun,': An order must be specified for Hermite window.']);
      end;      
      if sum(1-(size(win{2})==1))>1
	error('"order" must be a scalar or vector');
      end;
      info.R=length(win{2});
    case {'pbspline','phanning'}
      info.isfir=1;
      info.R=1;
    otherwise
      error([callfun,': ',winname,', unknown window type.']);
  end;

  info.name=win{1};
  info.win=win;
  info.funpars=win(2:end);
end;

if isnumeric(win)

  % We cannot know that the intention of the window is, so
  % we assume that it is a FIR window.
  info.isfir=1;

  Lwin=size(win,1);
  if ((dgtinfo.isreal) && (~isreal(win)))
    error([callfun,': ',winname,', window must be real valued.']);
  end;

  if ((dgtinfo.iseven==1) && (~iscentered(win)))
    error([callfun,': ',winname,', window must be whole point even.']);
  end;

  if dgtinfo.iseven==2
    error('ASSERT_WIN half-point even check not handled yet.');
  end;
  
  if mod(Lwin,dgtinfo.M)~=0
    error([callfun,': ',winname,', the length of the window must be divisable by M.']);
  end;

  if mod(Lwin,dgtinfo.a)~=0
    error([callfun,': ',winname,', the length of the window must be divisable by a.']);
  end;
  
  info.isfixed=1;
  info.name='numerical';
  info.Lwin=Lwin;
  info.R=size(win,2);

  g_dgt=win;
  % Shift the window if requested.
  if (dgtinfo.c_w>0)
    g_dgt=circshift(win,dgtinfo.c_w);
  end;

  info.g_dgt=g_dgt;
  info.g=win;
end;