Implementation of Flyvbjerg and Petersen's blocking method

The blocking method is used to obtain the actual standard deviation of a set of correlated data.

! !
! Flyvbjerg og Petersen
!
! this programme calculates the standard deviation of a set of
! correlated data using the method of H. Flyvbjerg and
! H.G. Petersen (1989) J. Chem. Phys., 91, 461--466.
!
! KM Tu 2011
!
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