function?d?=?mahalanobis（X?Mu?C）
%MAHALANOBIS?Mahalanobis?distance.
%???D?=?MAHALANOBIS（X?MU?C）?returns?the?Mahalanobis?distance?between
%???the?length?p?vectors?X?and?MU?given?the?p?by?p?covariance?matrix
%???C.?If?omitted?it?is?assumed?that?C?is?the?identity?matrix（單位矩陣/恒等矩陣）
%???EYE（p）.?If?either?X?or?MU?is?an?n?by?p?matrix?D?will?be?returned
%???as?an?n?by?g?matrix?where?n?is?the?number?of?rows?in?X?and?g?is
%???the?number?of?rows?in?MU?where?each?entry?i?j?corresponds?to?the
%???mahalanobis?distance?between?row?i?of?X?and?row?j?of?MU.?If?MU?is
%???simply?0?it?is?treated?as?the?origin?from?which?Mahalanobis
%???distance?to?X?is?calculated.?C?must?be?a?positive?definite
%???symmetric?matrix.
%
%???The?Mahalanobis?distance?between?vectors?X（i:）?and?MU（j:）?is
%???defined?as:
%
%???D（ij）?=?（（X（i:）?-?MU（j:））‘*INV（C）*（X（i:）?-?MU（j:）））.^（1/2）

%???Copyright?（c）?1999?Michael?Kiefte.

%???$Log$

error（nargchk（2?3?nargin））

if?isempty（X）?|?~isa（X?‘double‘）?|?~isreal（X）?|?