HP hp39gPlus User Guide - Page 156

Probability functions COMB PERM RANDOM HINT Number of combinations (without regard to order) of n things taken r at a time: n!/(r!(n-r)). COMB(n, r) Example COMB(5,2) returns 10. That is, there are ten different ways that five things can be combined two at a time.! Factorial of a positive integer. For non-integers, ! = Γ(x + 1). This calculates the gamma function. value! Number of permutations (with regard to order) of n things taken r at a time: n!/(r!(n-r)! PERM (n, r) Example PERM(5,2) returns 20. That is, there are 20 different permutations of five things taken two at a time. Random number (between zero and 1). Produced by a pseudo-random number sequence. The algorithm used in the RANDOM function uses a seed number to begin its sequence. To ensure that two calculators must produce different results for the RANDOM function, use the RANDSEED function to seed different starting values before using RANDOM to produce the numbers. RANDOM The setting of Time will be different for each calculator, so using RANDSEED(Time) is guaranteed to produce a set of numbers which are as close to random as possible. You can set the seed using the command RANDSEED. UTPC Upper-Tail Chi-Squared Probability given degrees of freedom, evaluated at value. Returns the probability that a χ2 random variable is greater than value. UTPC(degrees, value) 11-12 Using mathematical functions