function?plot_lc（rhoetamarkerpsreg_param）?
%PLOT_LC?Plot?the?L-curve.?
%?
%?plot_lc（rhoetamarkerpsreg_param）?
%?
%?Plots?the?L-shaped?curve?of?the?solution?norm?
%????eta?=?||?x?||??????if???ps?=?1?
%????eta?=?||?L?x?||????if???ps?=?2?
%?as?a?function?of?the?residual?norm?rho?=?||?A?x?-?b?||.??If?ps?is?
%?not?specified?the?value?ps?=?1?is?assumed.?
%?
%?The?text?string?marker?is?used?as?marker.??If?marker?is?not?
%?specified?the?marker?‘-‘?is?used.?
%?
%?If?a?fifth?argument?reg_param?is?present?holding?the?regularization?
%?parameters?corresponding?to?rho?and?eta?then?some?points?on?the?
%?L-curve?are?identified?by?their?corresponding?parameter.?
?
%?Per?Christian?Hansen?IMM?12/29/97.?
?
%?Set?defaults.?
if?（nargin==2）?marker?=?‘-‘;?end??%?Default?marker.?
if?（nargin?np?=?10;???????????????????????????%?Number?of?identified?points.?
?
%?Initialization.?
if?（ps??2）?error（‘Illegal?value?of?ps‘）?end?
n?=?length（rho）;?ni?=?round（n/np）;?
?
%?Make?plot.?
loglog（rho（2:end-1）eta（2:end-1））?ax?=?axis;?
if?（max（eta）/min（eta）?>?10?|?max（rho）/min（rho）?>?10）?
??if?（nargin?????loglog（rhoetamarker）?axis（ax）?
??else?
????loglog（rhoetamarkerrho（ni:ni:n）eta（ni:ni:n）‘x‘）?axis（ax）?
????HoldState?=?ishold;?hold?on;?
????for?k?=?ni:ni:n?
??????text（rho（k）eta（k）num2str（reg_param（k）））;?
????end?
????if?（~HoldState）?hold?off;?end?
??end?
else?
??if?（nargin?????plot（rhoetamarker）?axis（ax）?
??else?
????plot（rhoetamarkerrho（ni:ni:n）eta（ni:ni:n）‘x‘）?axis（ax）?
????HoldState?=?ishold;?hold?on;?
????for?k?=?ni:ni:n?
??????text（rho（k）eta（k）num2str（reg_param（k）））;?
????end?
????if?（~HoldState）?hold?off;?end?
??end?
end?
xlabel（‘residual?norm?||?A?x?-?b?||_2‘）?
if?（ps==1）?
??ylabel（‘solution?norm?||?x?||_2‘）?
else?
??ylabel（‘solution?semi-norm?||?L?x?||_2‘）?
end?
title（‘L-curve‘）?

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----
?????目錄???????????0??2009-10-15?21:37??L曲線程序\
?????文件????????1158??2003-12-16?21:08??L曲線程序\CGSVD.M
?????文件?????????794??2003-12-16?21:08??L曲線程序\CSVD.M
?????文件???????17767??2008-12-15?17:59??L曲線程序\data3.dat
?????文件????????1271??2003-12-16?21:08??L曲線程序\LCFUN.M
?????文件????????7585??2003-12-16?21:08??L曲線程序\L_CORNER.M
?????文件????????5495??2003-12-16?21:08??L曲線程序\L_CURVE.M
?????文件????????1890??2001-09-13?09:07??L曲線程序\plot_lc.m