min.m

几个关于多小波的程序

function [Smin,Imin] = min(S,varargin)

% MIN -- min function for symbolic constants
%
%        [Smin,Simin] = min(S,[],dim)
%
% This is the same as the usual MIN function, but for symbolic
% constants. It converts S to double, finds the position of the 
% smallest entry, and returns the original value at that position.
%
% This routine rejects matrices with symbolic variables.

% Copyright (c) 2004 by Fritz Keinert ([e-mail]),
% Dept. of Mathematics, Iowa State University, Ames, IA 50011.
% This software may be freely used and distributed for non-commercial
% purposes, provided this copyright statement is preserved, and
% appropriate credit for its use is given.
%
% Last update: Feb 20, 2004

if ~isnumeric(S)
    n = size(S);
    S = reshape(simplify(S(:)),n);
end

if issymbolic(S)
    error('MIN is not defined for symbolic variables');
end

n = size(S);
switch nargin
 case 2
% Smin = min(S,T)
  T = varargin{1};
  if ~isnumeric(T)
      m = size(T);
      T = reshape(simplify(T(:)),m);
  end
  if issymbolic(T)
      error('MIN is not defined for symbolic variables');
  end
  m = size(T);
  if (prod(m) == 1)
% T is scalar
      DS = double(S(:));
      DT = double(T);
      Smin = S(:);
      for i = 1:length(Smin)
	  if (DS(i) > DT)
	      Smin(i) = T;
	  end
	  Smin = reshape(Smin,n);
      end
      return
  elseif (prod(n) == 1)	  
% S is scalar
      DS = double(S);
      DT = double(T(:));
      Smin = T(:);
      for i = 1:length(Smin)
	  if (DT(i) > DS)
	      Smin(i) = S;
	  end
	  Smin = reshape(Smin,m);
      end
      return
  else
% both are matrices
      if (length(m) ~= length(n))
	  error('dimensions must agree');
      end
      if ~iszero(m-n)
	  error('dimensions must agree');
      end	  
      DS = double(S(:));
      DT = double(T(:));
      Smin = S(:);
      for i = 1:length(Smin)
	  if (DS(i) > DT(i))
	      Smin(i) = T(i);
	  end
	  Smin = reshape(Smin,n);
      end
      return
  end

 case {1,3}
  if (nargin == 1)
      lnd = 1; % leading nonzero dimension
      for i = 2:length(n)
	  if (n(lnd) == 1 & n(i) > 1)
	      lnd = i;
	  end
      end
  else
      lnd = varargin{2};
  end
  D = reshape(double(S(:)),n);
  [Dmin,Imin] = min(D,[],lnd);
  nn = [n(1:lnd-1),1,n(lnd+1:end)];
  Smin = sym(zeros(size(Dmin)));
  for i = 1:prod(nn)
      ind = index(nn,i);
      Smin(ind{:}) = S(ind{1:lnd-1},Imin(ind{:}),ind{lnd+1:end});
  end
end