F
Parallel Processing With Lists F - 1
12.Parallel Processing with Lists
Parallel processing is the idea that, generally, if a command can be applied to one or more individual arguments,
then it can also be extended to be applied to one or more sets of arguments. (Note: some examples assume
approximate mode.)
Some examples:
! Q!6=N returns dH, so fa!Q!Rh!6=N returns fdHQ!dH!d3HQh.
! a!Q!. returns H8, so fa!Q!ch!fQ!c!eh!. returns fH8!V8!aHh, and fa!Q!ch!Q!. returns
fH8!HQ!V8h.
General rules for parallel processing
As a rule-of-thumb, a given command can use parallel list processing if all the following are true:
! The command checks for valid argument types. Commands that apply to all object types, such as DUP,
SWAP, ROT, and so forth, do not use parallel list processing.
! The command takes exactly one, two, three, four, or five arguments, none of which may itself be a list.
Commands that use an indefinite number of arguments (such as "LIST) do not use parallel list processing.
! The command isn't a programming branch command (IF, FOR, CASE, NEXT, and so forth).
The remainder of this appendix describes how the many and various commands available on the calculator are
grouped with respect to parallel processing.
Group 1: Commands that cannot parallel process
A command must take arguments before it can parallel process, since a zero-argument command (such as
RAND, VARS, or REC) has no arguments with which to form a group.
Group 2: Commands that must use DOLIST to parallel process
This group of commands cannot use parallel processing directly, but can be "coerced" into it using the
DOLIST command (see Using D later in this appendix). This group consists of several subgroups:
! Stack manipulation commands. A stack manipulation command cannot parallel process because the
stack is manipulated as a whole and list objects are treated the same as any other object. Stack commands
(such as DROP) that take level 1 arguments will not accept level 1 list arguments.
! Commands that operate on a list as a whole. Certain commands accept lists as arguments but treat
them no differently than any other data object. They perform their function on the object as a whole without
respect to its elements. For example, "STR converts the entire list object to a string rather than converting
each individual element, and the = = command tests the level 1 object against the level 2 object regardless of
the objects' types.
! List manipulation commands. List manipulation commands will not parallel process since they operate
on list arguments as lists rather than as sets of parallel data. However, a list manipulation command can be
forced to parallel process lists of lists by using the DOLIST command. For example,
ff3!H!Vh!fa!Q!chh!"!`E6D:!1!4LE6D:!returns!fc!3H8h.
! Other commands that have list arguments. Because a list can hold any number of objects of any type,
it is commonly used to hold a variable number of parameters of various types. Some commands accept such
lists, and because of this are insensitive to parallel processing, except by using DOLIST.
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