function?[x0y0]?=?centroid（xy）
%
%?CENTROID?Center?of?mass?of?a?polygon.
%
%?[X0Y0]?=?CENTROID（XY）?
%???
%?Calculates?centroid?（center?of?mass）?of?planar?polygon?with?vertex?
%?coordinates?X?Y.
%?Z0?=?CENTROID（X+i*Y）?returns?Z0=X0+i*Y0?the?same?as?CENTROID（XY）.
%
%??Copyright?（c）?1995?by?Kirill?K.?Pankratov
%???????kirill@plume.mit.edu.
%???????06/01/95?06/07/95
%
%?Algorithm:
%??X0?=?Int{x*ds}/Int{ds}?where?ds?-?area?element
%??so?that?Int{ds}?is?total?area?of?a?polygon.
%??Using?Green‘s?theorem?the?area?integral?can?be?
%??reduced?to?a?contour?integral:
%??Int{x*ds}?=?-Int{x^2*dy}?Int{ds}?=?Int{x*dy}?
%??along?the?perimeter?of?a?polygon.
%??For?a?polygon?as?a?sequence?of?line?segments
%??this?can?be?reduced?exactly?to?a?sum:
%??Int{x^2*dy}?=?Sum{?（x_{i}^2+x_{i+1}^2+x_{i}*x_{i+1}）*（y_{i+1}-y_{i}）}/3;
%??Int{x*dy}?=?Sum{（x_{i}+x_{i+1}）（y_{i+1}-y_{i}）}/2.
%??Similarly
%??Y0?=?Int{y*ds}/Int{ds}?
%??where
%??Int{y*ds}?=?Int{y^2*dx}?=?...
%????????????=?Sum{?（y_{i}^2+y_{i+1}^2+y_{i}*y_{i+1}）*（x_{i+1}-x_{i}）}/3.
%

?%?Handle?input?......................
if?nargin==0?help?centroid?return?end
if?nargin==1
??sz?=?size（x）;
??if?sz（1）==2??????%?Matrix?2?by?n
????y?=?x（2:）;?x?=?x（1:）;
??elseif?sz（2）==2??%?Matrix?n?by?2
????y?=?x（:2）;?x?=?x（:1）;
??else
????y?=?imag（x）;
????x?=?real（x）;
??end
end?

?%?Make?a?polygon?closed?..............
x?=?[x（:）;?x（1）];
y?=?[y（:）;?y（1）];

?%?Check?length?.......................
l?=?length（x）;
if?length（y）~=l
??error（‘?Vectors?x?and?y?must?have?the?same?length‘）
end

?%?X-mean:?Int{x^2*dy}?................
del?=?y（2:l）-y（1:l-1）;
v?=?x（1:l-1）.^2+x（2:l）.^2+x（1:l-1）.*x（2:l）;
x0?=?v‘*del;

?%?Y-mean:?Int{y^2*dx}?................
del?=?x（2:l）-x（1:l-1）;
v?=?y（1:l-1）.^2+y（2:l）.^2+y（1:l-1）.*y（2:l）;
y0?=?v‘*del;

?%?Calculate?area:?Int{y*dx}?..........
a?=?（y（1:l-1）+y（2:l））‘*del;
tol=?2*eps;
if?abs（a）???disp（‘?Warning:?area?of?polygon?is?close?to?0‘）
??a?=?a+sign（a）*tol+（~a）*tol;
end
?%?Multiplier
a?=?1/3/a;

?%?Divide?by?area?.....................
x0?=?-x0*a;
y0?=??y0*a;

if?nargout?

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----
?????目錄???????????0??2016-04-08?22:05??MATGPR_R3\
?????目錄???????????0??2016-04-08?22:03??MATGPR_R3\analysis\
?????目錄???????????0??2014-01-20?21:00??MATGPR_R3\analysis\alternative\
?????目錄???????????0??2014-01-20?21:00??MATGPR_R3\analysis\alternative\gazdagmig+migrate.f90\
?????文件????????1697??2013-11-18?23:10??MATGPR_R3\analysis\alternative\gazdagmig+migrate.f90\gazdagmig.p
?????文件??????170496??2004-03-30?02:40??MATGPR_R3\analysis\alternative\gazdagmig+migrate.f90\migrate.exe
?????文件????????9368??2004-03-30?02:40??MATGPR_R3\analysis\alternative\gazdagmig+migrate.f90\migrate.f90
?????目錄???????????0??2014-01-20?21:00??MATGPR_R3\analysis\alternative\Splitstep_model+radar2d4.f90\
?????文件??????477244??2006-01-04?04:28??MATGPR_R3\analysis\alternative\Splitstep_model+radar2d4.f90\radar2d4.exe
?????文件???????32077??2006-01-04?04:28??MATGPR_R3\analysis\alternative\Splitstep_model+radar2d4.f90\radar2d4.f90
?????文件????????2209??2013-11-18?23:12??MATGPR_R3\analysis\alternative\Splitstep_model+radar2d4.f90\splitstep2dmodel.p
?????文件?????????931??2013-11-18?21:48??MATGPR_R3\analysis\BSplineWaveletFilter.p
?????文件????????7739??2016-04-01?17:34??MATGPR_R3\analysis\build2dmodel.p
?????文件?????????268??2013-11-18?21:49??MATGPR_R3\analysis\cbspldv.p
?????文件?????????826??2016-04-01?17:34??MATGPR_R3\analysis\cbsplwv.p
?????文件????????2161??2013-10-25?14:31??MATGPR_R3\analysis\centroid.m
?????文件????????1437??2013-12-18?01:57??MATGPR_R3\analysis\CentroidFrequency.p
?????文件????????1976??2014-11-13?01:29??MATGPR_R3\analysis\CurveletFilter.p
?????文件????????4393??2014-11-13?01:28??MATGPR_R3\analysis\CurveletSelectCoefficients.p
?????文件?????????369??2013-11-18?21:49??MATGPR_R3\analysis\dewow.p
?????文件????????2728??2016-04-01?17:34??MATGPR_R3\analysis\editmarkers.p
?????文件????????2225??2013-11-19?16:42??MATGPR_R3\analysis\editscanaxis.p
?????文件????????1527??2013-11-18?21:49??MATGPR_R3\analysis\equalize.p
?????文件????????2079??2013-11-19?22:50??MATGPR_R3\analysis\fdct_wrapping.p
?????文件?????????252??2013-11-19?22:50??MATGPR_R3\analysis\fdct_wrapping_window.p
?????目錄???????????0??2014-04-28?19:36??MATGPR_R3\analysis\fdtd\
?????文件?????????957??2013-10-26?12:21??MATGPR_R3\analysis\fdtd\blackharrispulse.m
?????文件????????1001??2013-10-26?12:18??MATGPR_R3\analysis\fdtd\finddt.m
?????文件????????2200??2013-10-26?11:51??MATGPR_R3\analysis\fdtd\finddx.m
?????文件????????2135??2014-04-28?19:36??MATGPR_R3\analysis\fdtd\getemproperties.p
?????文件?????????828??2013-10-26?12:17??MATGPR_R3\analysis\fdtd\gridinterp.m
............此處省略520個文件信息