Correlation isn’t a property of a pair of mathematical functions or a pair of physical systems, it’s a property of a pair of random variables.
“A and B are correlated” means “Observing A can change your probabilistic beliefs about B”.
If you already know that A and B are both sine waves, then neither has any belief-updating power over the others, there’s no randomness in the random variables.
(I know that’s not 100% precise… someone else please improve.)
Correlation isn’t a property of a pair of mathematical functions or a pair of physical systems, it’s a property of a pair of random variables.
“A and B are correlated” means “Observing A can change your probabilistic beliefs about B”.
If you already know that A and B are both sine waves, then neither has any belief-updating power over the others, there’s no randomness in the random variables.
(I know that’s not 100% precise… someone else please improve.)