function A=OMP(D,X,L)
% ÊäÈë²ÎÊý:
% D - ¹ýÍ걸×ֵ䣬עÒ⣺±ØÐë×ÖµäµÄ¸÷ÁбØÐë¾-¹ýÁ˹淶»¯
% X - ÐźÅ
% L - ϵÊýÖзÇÁãÔª¸öÊýµÄ×î´óÖµ£¨¿ÉÑ¡£¬Ä¬ÈÏΪDµÄÁÐÊý£¬ËٶȿÉÄÜÂý£©
% Êä³ö²ÎÊý:
% A - Ï¡ÊèϵÊý
if nargin==2
L=size(D,2);
end
P=size(X,2);
K=size(D,2);
for k=1:1:P,
a=[];
x=X(:,k);
residual=x;
indx=zeros(L,1);
for j=1:1:L,
proj=D'*residual;
[maxVal,pos]=max(abs(proj));
pos=pos(1);
indx(j)=pos;
a=pinv(D(:,indx(1:j)))*x;
residual=x-D(:,indx(1:j))*a;
if sum(residual.^2) < 1e-6
break;
end
end;
temp=zeros(K,1);
temp(indx(1:j))=a;
A(:,k)=sparse(temp);
end;
return;
