##### https://github.com/vegarant/spgl1

Tip revision:

**5b6ee1e77c0a24b8f50d6462478cc2a5b09f5622**authored by**Michael Friedlander**on**26 April 2016, 15:40:32 UTC****Move webpage to UBC.** Tip revision:

**5b6ee1e** spg_bp.m

```
function [x,r,g,info] = spg_bp(A,b,options )
%SPG_BP Solve the basis pursuit (BP) problem
%
% SPG_BP is designed to solve the basis pursuit problem
%
% (BP) minimize ||X||_1 subject to AX = B,
%
% where A is an M-by-N matrix, B is an M-vector, and SIGMA is a
% nonnegative scalar. In all cases below, A can be an explicit M-by-N
% matrix or matrix-like object for which the operations A*x and A'*y
% are defined (i.e., matrix-vector multiplication with A and its
% adjoint.)
%
% Also, A can be a function handle that points to a function with the
% signature
%
% v = A(w,mode) which returns v = A *w if mode == 1;
% v = A'*w if mode == 2.
%
% X = SPG_BP(A,B) solves the BP problem.
%
% X = SPG_BP(A,B,OPTIONS) specifies options that are set using
% SPGSETPARMS.
%
% [X,R,G,INFO] = SPG_BP(A,B,OPTIONS) additionally returns the
% residual R = B - A*X (which should be small), the objective gradient G
% = A'*R, and an INFO structure. (See SPGL1 for a description of this
% last output argument.)
%
% See also spgl1, spgSetParms, spg_bpdn, spg_lasso.
% Copyright 2008, Ewout van den Berg and Michael P. Friedlander
% http://www.cs.ubc.ca/labs/scl/spgl1
% $Id: spg_bp.m 1074 2008-08-19 05:24:28Z ewout78 $
if ~exist('options','var'), options = []; end
if ~exist('b','var') || isempty(b)
error('Second argument cannot be empty.');
end
if ~exist('A','var') || isempty(A)
error('First argument cannot be empty.');
end
sigma = 0;
tau = 0;
x0 = [];
[x,r,g,info] = spgl1(A,b,tau,sigma,x0,options);
```