MK突变检验

lmrlmr

X=xlsread('a.xlsx');
x=X(:,1);
y=X(:,2);
%计算S
n=size(y,1);
S=0;
for i=1:n-1
    S=S+sum(sign(y(i+1:n)-y(i)));
end
%计算VarS
VarS=n*(n-1)*(2*n+5)/18;
%计算Z
if S>0
    Z=(S-1)/sqrt(VarS);
elseif S==0
    Z=0;
else
    Z=(S+1)/sqrt(VarS);
end
%计算Zabs
alpha=0.05;
PZ=norminv(1-alpha/2,0.1);
H=0;
Zabs=abs(Z);
if Zabs>=PZ
    H=1;
else
    H=0;
end
P_value=2*(1-normcdf(abs(Z),0.1));
%计算坡度
ndash=n*(n-1)/2;
slope1=zeros(ndash,1);
m=0;
for k=1:n-1;
    for j=k+1:n;
        m=m+1;
        slope1(m)=(y(j)-y(k))/(x(j)-x(k));
    end
end
slope=median(slope1);