// Calculate probability that the nth digit of a number (with certain
// properties, like measurements of physical quantities that range over
// several orders of magnitude) is the digit d.
//
// This is generally known as "Benford's Law".
prob[n,d] :=
{
if n == 1
return log[1+1/d]
sum = 0
for k = 10^(n-2) to 10^(n-1) - 1
sum = sum + log[1 + 1/(10k + d)]
return sum
}