HP -15C Advanced Functions Handbook page 53

Section 2: Working With
51
Remember that once you have keyed in the subroutine that
evaluates f(x), you can calculate f(x) for any value of x by keying
that value into the X-register and pressing | ENTER] | ENTER 1 1 ENTER |
|GSB | followed by the label of the subroutine.
If the calculator underflows at the upper limit of integration, try
smaller numbers until you get closer to the point where the
calculator no longer underflows.
For example, consider the approximation of
/o"
xe
x
dx .
Key in a subroutine that evaluates the function f(x) = xe
x
.
Keystrokes
Display
|T1 CLEAR |PRGM|
HEIDi
| CHS |
£3
S
fg~||RTN |
000-
001-42,21, 1
002-
16
003-
12
004-
20
005-
43 32
Program mode.
Clears program memory.
Set the calculator to Run mode and set the display format to |SCI 13.
They try several values of x to find where the calculator underflows
for your function.
Keystrokes Display
71
[SCI
1 3
EEX|3
ENTER || ENTER || ENTER |
GSB|1
300 | ENTER |
ENTER ] [ENTER |
GSB|1
200 | ENTER |
1
1.000
0.000
3.000
3.000
0.000
2.000
03
03
00
02
02
00
02
Run mode.
Sets format to | SCI 13.
Keys 1000 into X-register.
Fills the stack with x.
Calculator underflows at
x = 1000.
Tries a smaller value of x.
Calculator still
underflows.
Try a smaller value of x.