A=rand(1000,1); %your array
sum1=0;
for i=1:length(A)
  sum1=sum1+A(i);
end
M=sum1/length(A); %the mean
sum2=0;
for i=1:length(A)
    sum2=sum2+ (A(i)-M)^2;
end
V=sum2/length(A); %Varaince