Function accepts size distribution in the form of two vectors: mesh size (d) and cumulative percent material retained R(d).

Example:
d = [0.08 0.50 1.25 2 4 6.3 8 12.5 16 40]
Rd = [95.61 87.71 82.45 79.78 73.28 66.98 63.21 55.4 49.91 23.95]

[k, n] = RRD(d, Rd)

Result of the function is a figure (diagram) as can be seen on screenshot and estimated parameters k and n.

Non-linear fitting routine is used to estimate the parameters.