# performing cwt and inverse cwt using fft

I'm currently working on my project related to implementing an speech enhancement algorithm on fpga which uses continuous wavelet with morel wavelet, how can i use efficient fft algorithm to calculate cwt and inverse cwt? i also came across this diagram from following paper https://aip.scitation.org/doi/citedby/10.1063/1.1147636which explains how to use fft to perform cwt but does not mentions how to calculate inverse cwt. Does the cross sign represents a complex multiplication?