Non-Keyboard Characters. You can display characters that don't
appear on the HP-28S keyboard by entering a numerical value and
executing CHR. There are also non-displayable characters that you
can print; for a list of all characters, see "STRING" in the Reference
Graphics Strings. The command LCD-
to string) returns a
graphics string that represents the current displayed image; the com-
mand -LCD (string to
displays the image represented by a
graphics-string argument. For details about these commands, see the
String Manipulations. The programs in "Displaying a Binary Inte-
ger", on page 257, show how to convert an object to string form,
count the number of characters, and join two strings.
Arrays can be one-dimensional (called vectors) or two-dimensional
(called matrices), and they can comprise real or complex numbers.
Chapter 11, "Vectors and Matrices," shows the basic calculations with
arrays. Part 1 included the following additional uses for arrays .
• Chapter 11 shows how to solve a system of n linear equations in n
unknowns by using a an n-element constant vector and an n
coefficient matrix. For details about this process and its accuracy,
see "ARRAY" in the Reference Manual.
• In chapter 12, "Statistics," the statistics data you entered was stored
in the current statistics matrix
In Algebraic Syntax. If an array is stored in a variable, you can re-
fer to elements in the array by using the variable name as a function.
For example, you could represent the sum of the third and fifth ele-
ments of a vector V as
Array Manipulations. The programs in "Summary Statistics" on
page 262, and "Median of Statistics Data," on page 270, demonstrate a
variety of array manipulations.