To Grav

Set your disk data as follows:

rmax=10000 pcs, h=100 pcs, rho = 1 msun/pc^3 (density), total mass =pi*rmax^2*rho*h
20 rings with rods at the mid radius rr(i) of each ring i, rr(i)= dr*i-dr/2
and read the rotation speeds at the outer radius rs(j) of each ring j, rs(j)=j*dr
radial width dr = rmax/20 for all rings

mass of each ring becomes mr(i)= 2*pi*rr(i)*dr* h*rho
mass of each rod in ring i becomes mrod(i)= mr(i)/120
length of all rods = h, diameter=0 (not important and not used)

position your rods around the half-ring mid radii, theta=1.5,4.5,.....,178.5 deg, then
find the accelereration caused by a single rod as a function of distance from the rod along a line
perpendicular to and bisecting the rod, (if in doubt see my paper), note the acceleraton blows up if the test mass
touches the rod, so that never happens, then
find the acceleration of a test mass at rs(j) on the theta =0 axis caused by TWO rods in ring i at positions + -
theta around the ring
then add up the effects of the rods by summing the effects of the 60 pairs to get
acceleration a(i,j) of a test mass at radius rs(j) caused by ring i INCLUDING THE CASE i=j, then
add up the effects of all the rings (i=1 to 20) on the test mass at locations rs(j), (j=1 to 20), to get A(j) the total
accelertion of the test mass at all locations rs(j)

That will get you through the forward problem. Notice you should now have the effects of each ring (at
density of 1) on a test mass at each speed radius j, and you are ready for the reverse problem. I believe all will
become clear after we get you through the reverse problem.

Good luck, Ken Nicholson