HP HP-28S - Flags

HP-28S
• To edit a program use the VISIT shortcut.
• If a variable contains the name of a program only then the program is
executed when the variable is recalled.
• If a program A contains the unquoted name of another program B,
the program B will be executed as a subroutine as soon as execution
of program A encounters the symbol B.
Symbolic
constants
These are: e, i, MINR, MAXR, π. See Direct Key Commands.
Flag 35 determines how these are evaluated:
• When set these symbolic constants evaluate to their symbolic form.
Use →NUM to convert them to numerical values.
• When clear these symbolic constants evaluate to their numerical
value.
Expressions,
Equations,
Functions
Flag 36 specifies how equations or functions with symbolic arguments are
evaluated:
• When set, the evaluation of an expression is taken only a single step
further by replacing variables with their contents (which may either be
another expression or a numerical value). EVAL may have to be
applied repeatedly to resolve all dependencies. Consider:
'A+B' 'A' STO A returns 'A+B'. After EVAL it is 'A+B+B' then
'A+B+B+B' etc.
• When clear, the variables are evaluated until a numerical result is
reached. If a symbolic name is undefined an error occurs. Do not try
the above excample with flag 36 clear because it will produce an
endless recursion loop!!
Consequences:
• In symbolic mode 'Q' 1/x returns 'INV(Q)' even if the variable Q
exists and has a numerical value. By pressing EVAL the expression is
evaluated and the numerical result returned.
• In numeric mode an error occurs if Q is not an existing variable.
Otherwise Q is evaluated and a numerical result is returned.
• Overall the symbolic evaluation mode seems to be more handy.
Flags
General For testing and modifying flags see TEST Menu.
1 – 64 User flags without predefined meaning.
31 – 64 System flags:
31 LAST activated. MODE Menu: LAST
32 Protocol. PRINT Menu: TRAC
33 Printhead right. See PRINT Menu.
34 Principal value. ALGEBRA Menu: ISOL and QUAD
35 Symbolic evaluation of constants. See Evaluation Rules.
36 Symbolic evaluation of functions. See Evaluation Rules.
37 – 42 Length of binary words (1-64), default is 64 BINARY menu: STWS
43, 44 Binary number base. 00=decimal, 01=binary, 02=octal, 03=hex
BINARY menu: DEC, HEX, OCT, BIN
45 Display in level 1: Single line or multi-line MODE menu: ML
46 (reserved)
46