HP 48gII - Manual (Page 651)

Page 21-2
„´@)HYP @SINH SINH Calculate sinh of level 1
1 #~„x „º 1 x SQ Enter 1 and calculate x 2
„´@)@MTH@ @LIST @ADD@ ADD Calculate (1+x 2 ),
/ / then divide
['] ~„x™ 'x'
„°@)@MEM@@ @)@DIR@@ @PURGE PURGE Purge variable x
` Program in level 1
_______________________ __________ _____________________
To save the program use:
[']~„gK
Press
J to recover your variable menu, and evaluate g(3.5) by entering the
value of the argument in level 1 ( 3.5`) and then pressing @@@g@@@.
The result is 1.2485…, i.e., g(3.5) = 1.2485. Try also obtaining g({1 2 3}),
by entering the list in level 1 of the display:
„ä1#2#3` and pressing @@@g@@@. The result now is
{SINH(1)/2 SINH(2)/5 SINH(3)/10}, if your CAS is set to
EXACT mode. If
your CAS is set to APPROXIMATE mode, the result will be {0.5876..
0.7253… 1.0017…}.
Global and local variables and subprograms
The program @@@g@@@, defined above, can be displayed as
« 'x' STO x SINH 1 x SQ ADD / 'x' PURGE »
by using
‚@@@g@@@.
Notice that the program uses the variable name x to store the value placed in
level 1 of stack through the programming steps
'x' STO . The variable x,
while the program is executing, is stored in your variable menu as any other
variable you had previously stored. After calculating the function, the
program purges (erases) the variable x so it will not show in your variable
menu after finishing evaluating the program. If we were not to purge the
variable x within the program its value would be available to us after program
execution. For that reason, the variable x, as used in this program, is referred
to as a global variable. One implication of the use of x as a global variable
is that, if we had a previously defined a variable with the name x, its value