nag_imldwt (c09cdc) computes the inverse one-dimensional multi-level discrete wavelet transform (DWT). This function reconstructs data from (possibly filtered or otherwise manipulated) wavelet transform coefficients calculated by nag_mldwt (c09ccc)
from an original set of data. The initialization function nag_wfilt (c09aac)
must be called first to set up the DWT options.
nag_imldwt (c09cdc) performs the inverse operation of nag_mldwt (c09ccc)
. That is, given a set of wavelet coefficients, computed by nag_mldwt (c09ccc)
using a DWT as set up by the initialization function nag_wfilt (c09aac)
, on a real data array of length
, nag_imldwt (c09cdc) will reconstruct the data array
from which the coefficients were derived. If the original input dataset is level
, then it is possible to terminate reconstruction at a higher level by specifying fewer than the number of levels used in the call to nag_mldwt (c09ccc)
. This results in a partial reconstruction.
The accuracy of the wavelet transform depends only on the floating point operations used in the convolution and downsampling and should thus be close to machine precision.