function?astardemo_Hong
%ASTARDEMO?Demonstration?of?ASTAR?algorithm
%
%???Copyright?Bob?L.?Sturm?Ph.?D.?Assistant?Professor
%???Department?of?Architecture?Design?and?Media?Technology
%?????formerly?Medialogy
%???Aalborg?University?i?Ballerup
%?????formerly?Aalborg?University?Copenhagen
%???$Revision:?0.1?$??$Date:?2011?Jan.?15?18h24:24$

n?=?20;???%?field?size?n?x?n?tiles??20*20的界面
wallpercent?=?0.15;??%?this?percent?of?field?is?walls???45%的界面作為阻礙物（墻）

%?create?the?n?x?n?FIELD?with?wallpercent?walls?containing?movement?costs?
%?a?starting?position?STARTPOSIND?a?goal?position?GOALPOSIND?the?costs?
%?A?star?will?compute?movement?cost?for?each?tile?COSTCHART?
%?and?a?matrix?in?which?to?store?the?pointers?FIELDPOINTERS
[field?startposind?goalposind?costchart?fieldpointers]?=?...
??initializeField（nwallpercent）;???%初始化界面

%?initialize?the?OPEN?and?CLOSED?sets?and?their?costs
setOpen?=?[startposind];?setOpenCosts?=?[0];?setOpenHeuristics?=?[Inf];
setClosed?=?[];?setClosedCosts?=?[];
movementdirections?=?{‘R‘‘L‘‘D‘‘U‘‘DR‘‘DL‘‘UR‘‘UL‘};

%?keep?track?of?the?number?of?iterations?to?exit?gracefully?if?no?solution
counterIterations?=?1;

%?create?figure?so?we?can?witness?the?magic
axishandle?=?createFigure（fieldcostchartstartposindgoalposind）;

%?as?long?as?we?have?not?found?the?goal?or?run?out?of?spaces?to?explore
while?~max（ismember（setOpengoalposind））?&&?~isempty（setOpen）??%ismember（AB）返回與A同大小的矩陣，其中元素1表示A中相應位置的元素在B中也出現，0則是沒有出現
??%?for?the?element?in?OPEN?with?the?smallest?cost
??[temp?ii]?=?min（setOpenCosts?+?setOpenHeuristics）;???%從OPEN表中選擇花費最低的點tempii是其下標（也就是標號索引）
??%?find?costs?and?heuristic?of?moving?to?neighbor?spaces?to?goal
??%?in?order?‘R‘‘L‘‘D‘‘U‘
??[costsheuristicsposinds]?=?findFValue（setOpen（ii）setOpenCosts（ii）?...
????fieldgoalposind‘euclidean‘）;???????%擴展temp的四個方向點，獲得其坐標posinds，各個方向點的實際代價costs，啟發代價heuristics
??%?put?node?in?CLOSED?and?record?its?cost
??setClosed?=?[setClosed;?setOpen（ii）];?????%將temp插入CLOSE表中
??setClosedCosts?=?[setClosedCosts;?setOpenCosts（ii）];??%將temp的花費計入ClosedCosts
??%?update?OPEN?and?their?associated?costs??更新OPEN表?分為三種情況
??if?（ii?>?1?&&?ii?????setOpen?=?[setOpen（1:ii-1）;?setOpen（ii+1:end）];
????setOpenCosts?=?[setOpenCosts（1:ii-1）;?setOpenCosts（ii+1:end）];
????setOpenHeuristics?=?[setOpenHeuristics（1:ii-1）;?setOpenHeuristics（ii+1:end）];
??elseif?（ii?==?1）
????setOpen?=?setOpen（2:end）;???%temp是OPEN表的第一個元素，刪除temp
????setOpenCosts?=?setOpenCosts（2:end）;
????setOpenHeuristics?=?setOpenHeuristics（2:end）;
??else?????%temp是OPEN表的最后一個元素，刪除temp
????setOpen?=?setOpen（1:end-1）;
????setOpenCosts?=?setOpenCosts（1:end-1）;
????setOpenHeuristics?=?setOpenHeuristics（1:end-1）;
??end
??%?for?each?of?these?neighbor?spaces?assign?costs?and?pointers;?
??%?and?if?some?are?in?the?CLOSED?set?and?their?costs?are?smaller?
??%?update?their?costs?and?pointers
??for?jj=1:length（posinds）??????%對于擴展的四個方向的坐標
???