Rms-func
rms function returns the root mean square of a vector.
The rms value for a set of n values is given by:
double rms(dataset vd)
vd
Return the root mean square of a vector.
Note: Missing values in vd won't be counted.
//Calculate the root mean square of a vector. yr = rms(col(A));
Ss, StdDev, StdDevP