HP 50g Graphing Calculator - Manual (Page 259)

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The figure below shows the RPN stack before pressing the K key:
Composing and decomposing lists
Composing and decomposing lists makes sense in RPN mode only. Under such
operating mode, decomposing a list is achieved by using function OBJ . With
this function, a list in the RPN stack is decomposed into its elements, with stack
level 1: showing the number of elements in the list. The next two screen shots
show the stack with a small list before and after application of function OBJ :
Notice that, after applying OBJ , the elements of the list occupy levels 4:
through 2:, while level 1: shows the number of elements in the list.
To compose a list in RPN mode, place the elements of the list in the stack, enter
the list size, and apply function LIST (select it from the function catalog, as
follows: ‚N‚é, then use the up and down arrow keys (—˜) to
locate function LIST). The following screen shots show the elements of a list of
size 4 before and after application of function LIST:
Note: Function OBJ applied to a list in ALG mode simply reproduces the list,
adding to it the list size:
Operations with lists of numbers
To demonstrate operations with lists of numbers, we will create a couple of
other lists, besides list L1 created above: L2={-3,2,1,5}, L3={-6,5,3,1,0,3,-4},
L4={3,-2,1,5,3,2,1}. In ALG mode, the screen will look like this after entering
lists L2, L3, L4: