Spherical coordinate system (r, θ, φ) ---> Cartesian coordinate system (x, y, z)
x=rsinθcosφ
y=rsinθsinφ
z=rcosθ
Cartesian coordinate system (x, y, z) ---> Spherical coordinate system (r, θ, φ)
r= sqrt(x^2 + y^2 + z^2)
φ= arctan(y/x)
θ= arcs(z/r)