j0, j1, jn - Bessel functions of the first kind

Definition	#include <math.h> double j0(double x); double j1(double x); double jn(int n, double x); The functions j0, j1 and jn calculate the Bessel functions of the first kind for floating-point values x and the integer orders 0, 1 or n.
Return val. See also	Bessel function for x. y0, y1, yn