% C = dct1mtx(M)
% Provide the type I discrete cosine
% transform matrix
%

function C = dct1mtx(M);
for I = 1:M+1
  for L = 1:M+1
    C(I,L)=sqrt(2/M)*cos((pi/M)*(L-1)*(I-1));
  end
end

D(1,1)=0.5;
D(1,M+1)=0.5;
D(M+1,1)=0.5;
D(M+1,M+1)=0.5;

x = 1/sqrt(2);
D(2:M,2:M)=ones(M-1,M-1);
D(1,2:M)=x*ones(1,M-1);
D(2:M,1)=x*ones(M-1,1);
D(M+1,2:M)=x*ones(1,M-1);
D(2:M,M+1)=x*ones(M-1,1);

C=D.*C;