better structure. most of task 1 done

nbody/reference/notes.md

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+###
+
+# Comparing with the analytical potential
+
+Plot a log-log plot of rho(r):
+- the discrete solution has poissonian error: 1/sqrt(N) where N is the number of particles in the bins
+
+=> ensure the discretization is consistent
+
+
+# Comparing forces
+- Use newtons law by considering only the inner shells:
+F_i = GM(R_i)/R_i^2
+
+
+=> this should all be done with the .ascii file (All particles, not yet meshed)
+
+
+
+
+## Task2
+a) start with only the monopole and compare with the direct summation
+only then build the tree code