% A_f1d: implements the sensing matrix/operator A
% refer to At_f:  implements the sensing matrix/operator AT (A transposed)
% Written by Thong Do, JHU, 2007
% modified, Feb. 2008

function b = A_f1d(x, select_vect, rand_vect,Phi_B, blk_size)
% Input parameters
% x: N vector
% b: K vector
% select_vect: vector that contains measurement indices randomly choosen
% rand_vect: vector that randomizes samples
% Phi_B: block operator: 

% Find out the length of the input signal;
N = length(x);
% Determine the block size of the operator;
blk_size=length(Phi_B);

% Pre-randomize the signal;
if min(rand_vect) == 1
    % Random permutation; 
    x(rand_vect) = x;
elseif min(rand_vect)==0
    % Random sign flipping; 
    x = x.*rand_vect;
end
x_ = reshape(x,n,n);
fx = Phi1*x*Phi2;
fx = fx(:);
b = fx(select_vect);