D (function)

d(n,x)
Probability mass function of d(3,6) and probability density function of the normal distribution with the same mean and standard deviation.
Distribution	normal (if n > 1)
Mean	$n*(x+1)/2$
Standard deviation	$\sqrt{n*(x^2-1)/12}$

d(n,x) is a pseudo-random number function used in NetHack to simulate the rolling of multiple dice. The range of values is between n and n*x inclusive (that is, n ≤ d(n,x) ≤ n*x). It is equivalent to ndx in D notation, or rolling n independent dice with x sides each and summing the results.

References

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