What is the formula for catenary calculation?

z = -H/g (cosh (gx/H)-1) where z = vertical distance

H = Horizontal component of cable force

g = weight of cable / unit of lenght

x = horizontal distance and dz/dx = -sinh(gx/H) V = - H sinh(gx/H) where V = vertical component of cable force N = H - gz where N = tension force in the cable