Simulating the randIntNoRep( command on the TI 83

Question

The randIntNoRep( command has been released for the TI-84+/SE calculator on OS 2.53MP and above.

The command is used when you need to create a list of numbers in random order in which no integer is repeated. It is very useful for shuffling a sequence of any numbers. How can I implement this functionality on an earlier version (OS or device-wise)?

Answer 1

This can be achieved by creating a list of random numbers, and using it to sequence a second list of the numbers that you want randomized.

For example, randomizing a 52 card deck and saving it as a list can be done easily with randIntNoRep( :

:randIntNoRep(0,51→L₁

This can be simulated using the following code:

:rand(52→L₂
:seq(X,X,0,51→L₁
:SortA(L₂,L₁

L₂ is set to contain a set of 52 random values. L₁ is set to contain the numbers that will be randomized. By sequencing the lists in ascending order, the same method can be achieved as using randIntNoRep(.

Answer 2

You can randomize a list by swapping its elements, like this.

:For(F,1,dim(L1))
:    iPart(dim(L1)rand+1)->R
:    L1(R)->T
:    L1(F)->L1(R)
:    T->L1(F)
:End

This randomize L1, assuming L1 has all the elements you want it to.