HP 10413 Datasheet download pdf (Page 281)

281

PERM(n,r)

This function gives the value of

P using the

formula

()!

−

Eg. How many ways can 3 Math, 4 English, and 6 German books be

arranged on a shelf if all the books from a subject must be together?

Ans:

()

346

3!PPP×× ×

RANDOM

This function supplies a random 12 digit

number between zero and one. If you want a

series of random numbers, just keep pressing

ENTER after the first one.

Eg. Produce a set of random integers

between 5 and 15 inclusive.

Use the expression INT(RANDOM*11)+5

The RANDOM*11 produces a range from 0 to

10.999999. This is then dropped down to the

integer below by the INT function, giving a

range of integers 0,1,2,3,...,10. The

final adding of 5 gives the correct range.

The

RANDSEED

command

It is important to realize that these are not truly random numbers. Inside the

calculator is a mathematical procedure (an algorithm) which uses a ‘seed’

number to produce them. Unfortunately, taken straight out of the box, two

hp 39g+’s will produce exactly the same sequence of “random” numbers!

This can be a problem in that, for example, a class set of calculators doing a

simulation of dice would all produce the same numbers.

The simple solution is to seed the random

number algorithm with different values for each

machine. This is done using the function

RANDSEED(…) and, providing each person

uses a different number, it should only be necessary to do it once (unless the

calculator is reset). The simplest method is to use RANDSEED(Time) since

the value of Time will be different on each calculator.

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HP 10413 Datasheet Page 281