# Random function coupled to a non-random function question.

 P: 6 Hello and thank you in advance for anyone taking time to respond. I working on formulating a theory for elastodynamics, but my statistics is admittedly weak. I'm trying to find a relationship between a non random function and a random function, for example, the covariance. =some 2 point probability for 2 random functions. These are discrete random variables, so the result is usually calculated numerically or by experimental observation. The problem I'm having is what if B(y) is non-random (ie deterministic) and continuous (not discrete)? I understand there is a discrete and integral formulation for discrete and continuous functions respectively, but I keep getting stuck. Its like I'm trying to find a connection that shouldn't be there, but they always come up in the formulation. Can anyone give me an idea of where to start?
 Sci Advisor P: 6,106 If B(y) is not random, then = B(y).
 P: 6 Ah, not what I wanted to hear (=0 centered fluctuations). What if B(y) is a binary characteristic function that is 1 inside a specified volume size within the total volume(though its position is not known) and zero otherwise?