what is the isotropic function of correlation is a isotropic correlation function periodic which isotropic correlation function is characterized by $l? is the length scale is the distance of each point are the correlation functions periodic or isotropic? what kind of correlation function is there which correlation functions are isotropic what is isotropic function is correlation periodic what is the function of correlation what is the correlation function what is isotropic correlation? which type of correlation is isotropic what type of correlation is r which isotropic correlation function is characterized by $l? what correlation function is the relationship of the length-scale and the distance of each point? is the length-scale a characteristic of correlation? what is the name of a periodic correlation function what is the function of a isotropic correlation is an isotropic correlation functions periodic