Function to find the standard deviation of series .
def sd ( arr , n ) : NEW_LINE INDENT sum = 0 ; NEW_LINE for i in range ( n ) : NEW_LINE INDENT sum = sum + ( ( arr [ i ] - mean ( arr , n ) ) * ( arr [ i ] - mean ( arr , n ) ) ) ; NEW_LINE DEDENT sdd = sum / n ; NEW_LINE return sdd ; NEW_LINE DEDENT