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padto(x,n), x a REAL vector or matrix, n > 0 an integer

Keywords: time series
padto(x,n) creates a new matrix or vector from REAL vector or matrix x
by adding n - nrows(x) rows of all zeros so as to bring the total number
of rows to n.  When n < nrows(x), the last nrows(x) - n rows of x are
deleted to bring the number down to n.  n must be a positive integer.

The principal use of padto() is to add zeros to a time series after
subtracting the mean or other estimate of trend but before computing its
Fourier transform, as in rft(padto(x-sum(x)/nrows(x),S)), where S is the
number of frequencies desired.  If x has several columns, they all get
padded simultaneously.

  Cmd> padto(vector(1,2,2)',4) # pad row vector to matrix with 4 rows
  (1,1)           1           2           2
  (2,1)           0           0           0
  (3,1)           0           0           0
  (4,1)           0           0           0

Gary Oehlert 2003-01-15