Does anybody know about any type of methods how to calucalte/estimate the number of the zeros of complex waves (periodic functions as superposition of many harmonic waves) within a given period [0,x] under the condition that the wave function is even? - It is indeed about the number of zeros and not determining the zeros themselves.
Does anybody knows about problems rising in other disciplines like physiscs where the number of such zeros are studied and essential?
Alternatively, if there might be a proof that such method can not generally exist (for instance because of a type of uncertainty principle), it would be also very helpful.
Many thanks
