sigma_error.adb running, n= 100
x 1 .. 100 
sum x^2 - (sum x)^2/n  sigma1 :=  2.88661E+01
sum(x-mean)2/n  sigma2 :=  2.88661E+01
x 10 .. 1000 
sum x^2 - (sum x)^2/n  sigma1 :=  2.88660E+02
sum(x-mean)2/n  sigma2 :=  2.88661E+02
x 100 .. 10000 
sum x^2 - (sum x)^2/n  sigma1 :=  2.88661E+03
sum(x-mean)2/n  sigma2 :=  2.88661E+03
x 1000 .. 100000 
sum x^2 - (sum x)^2/n  sigma1 :=  2.88661E+04
sum(x-mean)2/n  sigma2 :=  2.88661E+04
x 10000 .. 1000000 
sum x^2 - (sum x)^2/n  sigma1 :=  2.88661E+05
sum(x-mean)2/n  sigma2 :=  2.88661E+05
x 10001 .. 10100 
sum x^2 - (sum x)^2/n  sigma1 :=  2.89772E+01
sum(x-mean)2/n  sigma2 :=  2.88661E+01