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JuliaDSP / Wavelets.jl

A Julia package for fast discrete wavelet transforms and utilities
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Allow mutating versions to have differing precisions #53

Closed JeffFessler closed 4 years ago

JeffFessler commented 4 years ago

The current implementations of the mutating versions of the transforms require that the input array x and output array y have the same eltype:

function _dwt!(y::AbstractVector{T}, x::AbstractVector{T},
                filter::OrthoFilter, L::Integer, fw::Bool) where T<:Number

It would be useful to relax this restriction, e.g.:

function _dwt!(y::AbstractVector{Ty}, x::AbstractVector{Tx},
                filter::OrthoFilter, L::Integer, fw::Bool) where {Tx<:Number, Ty<:Number}

Note that the most basic "do nothing" transform in the code reverts to simply copyto!(y,x), and copyto! itself does not require the arguments do have the same eltype. (Of course you get and InexactError if you try to copy from arbitrary Floats to Ints, or Real to Complex, but if you do precision changes like Float32 to Float64 then copyto! takes care of the conversion for you. I'd be willing to try to make PR to provide this generality, because I think it just requires some changes to the function declarations, but I wanted to see first if there are objections or drawbacks. Edit: I needed this for my work so I made the PR #54.

gummif commented 4 years ago

Thanks for the PR. A new version has been released with the changes.