function?[xstatushistory]?=?l1_ls_nonneg（Ain1in2varargin）%varargin表示可以輸入多個變量
%
%?l1-Regularized?Least?Squares?Problem?Solver?//L1范數(shù)的最小化的求解
%
%???l1_ls?solves?problems?of?the?following?form://L1范數(shù)的如下形式
%
%???????minimize???||A*x-y||^2?+?lambda*sum（x_i）
%???????subject?to?x_i?>=?0?i=1...n
%
%???where?A?and?y?are?problem?data?and?x?is?variable?（described
%???below）.%A和y是問題數(shù)據(jù)x是變量
%
%?CALLING?SEQUENCES
%???[xstatushistory]?=?l1_ls_nonneg（Aylambda?[tar_gap[quiet]]）
%???[xstatushistory]?=?l1_ls_nonneg（AAtmnylambda?[tar_gap[quiet]]））
%
%???if?A?is?a?matrix?either?sequence?can?be?used.
%???if?A?is?an?object?（with?overloaded?operators）?At?m?n?must?be
%???provided.
%
%?INPUT
%???A???????:?mxn?matrix;?input?data.?columns?correspond?to?features.
%
%???At??????:?nxm?matrix;?transpose?of?A.//A的轉(zhuǎn)置
%???m???????:?number?of?examples?（rows）?of?A//樣本數(shù)目
%???n???????:?number?of?features?（column）s?of?A//特征數(shù)目
%
%???y???????:?m?vector;?outcome.//m維向量。輸出
%???lambda??:?positive?scalar;?regularization?parameter//正的標量，規(guī)則化參數(shù)
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%???tar_gap?:?relative?target?duality?gap?（default:?1e-3）//相關(guān)目標的對偶關(guān)系
%???quiet???:?boolean;?suppress?printing?message?when?true?（default:?false）
%
%???（advanced?arguments）
%???????eta?????:?scalar;?parameter?for?PCG?termination?（default:
%???????1e-3）//標量終止條件
%???????pcgmaxi?:?scalar;?number?of?maximum?PCG?iterations?（default:
%???????5000）//標量，最大的迭代次數(shù)。
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%?OUTPUT
%???x???????:?n?vector;?classifier//n個向量分類器
%???status??:?string;?‘Solved‘?or?‘Failed‘//狀態(tài):解決或失敗
%
%???history?:?matrix?of?history?data.?columns?represent?（truncated）?Newton
%?????????????iterations;?rows?represent?the?following:
%????????????-?1st?row）?gap
%????????????-?2nd?row）?primal?objective
%????????????-?3rd?row）?dual?objective
%????????????-?4th?row）?step?size
%????????????-?5th?row）?pcg?iterations
%????????????-?6th?row）?pcg?status?flag
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%?USAGE?EXAMPLES
%???[xstatus]?=?l1_ls_nonneg（Aylambda）;
%???[xstatus]?=?l1_ls_nonneg（AAtmnylambda0.001）;
%
?
%?AUTHOR????Kwangmoo?Koh?
%?UPDATE????Apr?10?2008
%
%?COPYRIGHT?2008?Kwangmoo?Koh?Seung-Jean?Kim?and?Stephen?Boyd

%------------------------------------------------------------
%???????INITIALIZE
%------------------------------------------------------------

%?IPM?PARAMETERS
MU??????????????=?2;????????%?updating?parameter?of?t//參數(shù)t的更新
MAX_NT_ITER?????=?400;??????%?maximum?IPM?（Newton）?iteration//最大迭代次數(shù)

%?LINE?SEARCH?PARAMETERS
ALPHA???????????=?0.01;?????%?minimum?fraction?of?decrease?in?the?objective//減少的最小分數(shù)
BETA????????????=?0.5;??????%?stepsize?decrease?factor//步長
MAX_LS_ITER?????=?100;??????%?maximum?backtracking?line?search?iteration//最大回溯線查找迭代

%?VARIABLE?ARGUMENT?HANDLING
%?if?the?second?argument?is?a?matrix?or?an?operator?the?calling?sequence?is
%???l1_ls（AAtylambdamn?[tar_gap[quiet]]））
%?if?the?second?argument?is?a?vector?the?calling?sequence?is//如果是向量調(diào)用下面的參數(shù)
%???l1_ls（Aylambda?[tar_gap[quiet]]）

%?
%?if?（?（isobject（varargin{1}）?||?~isvector（varargin{1}）