Pad extends the input data set (of type VectorType) with zeros according
to the choices that the user makes in the parameter window. The user can
choose to place the extra zeros at the beginning or at the end of the data
set. The user can choose one of four algorithms for adding zeros, and for
three of them the user must supply a value for an appropriate parameter.
The four choices are
The way that this unit acts on VectorType inputs varies according to
the type. A pure VectorType
will be extended as described above. If the data are irregularly
sampled, they will be extended with a regular spacing equal to the size
of the first or last data interval, according to whether they are placed
at the beginning or the end. A SampleSet
or a ComplexSampleSet
will be extended as described above and its sampling rate will not be changed.
A
Spectrum
or ComplexSpectrum
will be extended as described above; its frequency resolution will not
be changed, and the parameter nFull (the number of points in the
full data set from which it might have been derived by a Fourier transform)
is increased to the new size. If the spectral data are narrow-band,
the new length of the extended set is interpreted as the size of nFull,
not the size of the bandwidth of the data held in the object. Note that
Spectrum and ComplexSpectrum data sets cannot be extended at the front,
since it does not make sense to add points below zero frequency. More details
are given in the documentation for these spectral types. If the input set
is a Histogram, then the data set will be extended as described above.
If the zeros are to be added at the beginning and the first delimiter is
negative infinity, then nothing is done; similarly if the zeros are to
be added at the end and the last delimiter is positive infinity, nothing
is done.
The default choices are: add data at the end, reaching a given multiple
of the existing data set length, with that multiple equal to 1. This
does nothing, since the final length equals the initial one.