HP -15C Advanced Functions Handbook page 16

14 Section 1: Using [SOLVE | Effectively
Keystrokes Display
FRTI
HOOD
0.0000
7.5137
Function value.
Restores stack.
The day was March 7th. Convert the fractional portion of the
number to decimal hours and then to hours, minutes, and seconds.
Keystrokes
240
[T1| -HH. MS |
Display
0.5137
12.3293
12.1945
Fractional portion of day.
Decimal hours.
Hours, minutes, seconds.
Explorer Coulerre should expect to see the sun on March 7th at
12
h
19
m
45
s
(Coordinated Universal Time).
By examining Coulerre's function f(t), you realize that it can have
as many as four real roots—three positive and one negative. Try to
find additional positive roots by using | SOLVE | with larger positive
estimates.
Two larger, positive
estimates.
No root found.
Last estimate tried.
A previous estimate.
Nonzero value of function.
Restores stack to original
state.
Again, no root found.
Approximately same
estimate.
A previous estimate.
Same function value.
Keystrokes
1 000 1 ENTER | 1 1 00
rri i SOLVE i [A]
s
[MI
EB
LUtEBELRl]
Display
1,100
Error 8
278.4497
276.7942
7.8948
278.4497
LKB
LIB
Error 8
278.4398
278.4497
7.8948
You have found a positive local minimum rather than a root. Now
try to find the negative root.