



 
Murtaza, There are one pass expressions for the variance s^{2} and then the standard deviation is the square root of the variance. One such expression is If you can keep a running total of the data values x_{i}, the squares of the data values x_{i}^{2} and the number of data values then you can assemble this expression after all the data is read once. This expression only uses the data values and the number of data values and not the order in which the values are read. I hope this helps,  


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