HP 15c - Manual (Page 225)

Appendix D: A Detailed Look at _ 225
In order to find the first time at which the height is 107 meters, use initial
estimates of 0 and 1 second and execute _ using B.
Keystrokes Display
| ¥
Run mode.
0 v
0.0000
Initial estimates.
1
1
´ _
B 4.1718
The desired root.
) 4.1718
A previous estimate of the root.
) 0.0000
Value of f(t) at root.
It takes 4.1718 seconds for the ridget to reach a height of exactly 107
meters. (It takes approximately two seconds to find this solution.)
However, suppose you assume that the function h(t) is accurate only to the
nearest whole meter. You can now change your subroutine to give f(t) = 0
whenever the calculated magnitude of f(t) is less than 0.5 meter. Change
your subroutine as follows:
Keystrokes Display
| ¥ 000-
Program mode.
t “ 006 006– 30
Line before n instruction.
| a 007– 43 16
Magnitude of f(t).
. 008– 48 Accuracy
5 009– 5
| T 7 010–43,30, 7
Test for x > y and return
zero if accuracy >
magnitude (0.5 > | f(t) | ).
| ` 011– 43 35
| T 0 012–43,30, 0 Test for x ≠ 0 and restore
| K 013– 43 36 f(t) if value is nonzero.