. 2021 Aug 27;14(5):1689–1710. doi: 10.1007/s12559-021-09910-0

Table 5.

Neural network complexity comparison

Neural network	Complexity order	Cost estimation (FLOPs)
		PPG	PPG + ECG
Fully connected	$O (l e n g t h \times {(v e c t o r d i m e n s i o n)}^{2})$	$\sim 625$	$\sim 2500$
LSTM	$O (l e n g t h \times {(v e c t o r d i m e n s i o n)}^{2})$	$\sim 625$	$\sim 2500$
WaveNet	$O (l e n g t h \times {(v e c t o r d i m e n s i o n)}^{2} \times k e r n e l s i z e)$	$\sim 1850$	$\sim 7500$
WaveNet + LSTM	$O (l e n g t h \times {(v e c t o r d i m e n s i o n)}^{2} \times k e r n e l s i z e)$	$\sim 1850$	$\sim 7500$
ResNet + LSTM	$O (l e n g t h \times {(v e c t o r d i m e n s i o n)}^{2} \times k e r n e l s i z e)$	$\sim 4375$	$\sim 17, 500$