I am sorry I do not have a code but can refer a book : DSP using Matlab by R J Schilling and S L Harris. Explain the FLOPs for estimating computational complexity of convolution and correlation .
DSP algorithms for complexity by Hari Krishna Garg ( I referred long ago !!)
MATLAB does not support FLOP count anymore. This is mainly because counting the FLOPs has become increasingly cumbersome and the number of arithmetic operations has generally lost its significance in the context of computational or time complexity of algorithms. I think the best way to evaluate computational complexity of a signal processing algorithm in comparison to other algorithms in MATLAB is to calculate and compare the time taken to run each algorithm using "tic" and "toc" commands.