qqplot.m

这是在网上下的一个东东

%
% qqplot(data)
%
% Produces a QQ plot of the data.  
%
function f=qqplot(data)
m=mean(data);
s=std(data);
n=length(data);
x=sort(data);
q=zeros(n,1);
xqm=zeros(n,1);
for i=1:length(x)	
  q(i)=(i-0.5)/n;
  xqm(i)=phiinv(q(i));
end
plot(xqm,x,'k+');
hold on
%
% Plot the theoretical line for the given mean and standard deviation
%
plot([xqm(1) xqm(n)],[m+phiinv(0.5/n)*s m+phiinv((n-0.5)/n)*s ]  ,'k--');