nag_idwt (c09cbc) computes the inverse one-dimensional discrete wavelet transform (DWT) at a single level. The initialization function
nag_wfilt (c09aac) must be called first to set up the DWT options.
nag_idwt (c09cbc) performs the inverse operation of
nag_dwt (c09cac). That is, given sets of
${n}_{c}$ approximation coefficients and detail coefficients, computed by
nag_dwt (c09cac) using a DWT as set up by the initialization function
nag_wfilt (c09aac), on a real data array of length
$n$,
nag_idwt (c09cbc) will reconstruct the data array
${y}_{i}$, for
$\mathit{i}=1,2,\dots ,n$,
from which the coefficients were derived.
None.
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.
None.