HP 15c User Manual
Page 15
Section 1: Using
_ Effectively
15
In Run mode, key in the five coefficients:
Keystrokes
Display
|¥
Run mode.
4.2725 “8”
4.2725 -08
O4
4.2725 -08
Coefficient of t
4
.
1.9931
”“
5
” O3
-1.9931 -05
Coefficient of t
3
.
1.0229
“3”
1.0229 -03
O2
0.0010
Coefficient of t
2
.
3.7680
“1”
3.7680 -01
O1
0.3768
Coefficient of t.
2.8806
” O0
-2.8806
Constant term.
Because the desired solution should be between 1 and 32, key in these values for initial
estimates. Then use _ to find the roots.
Keystrokes
Display
1
v
1.0000
32
32
Initial Estimates.
´_A
7.5137
Root found.
)
7.5137
Same previous estimate.
)
0.0000
Function value.
|(|(
7.5137
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
Display
´ q
0.5137
Fractional portion of day.
24
*
12.3293
Decimal hours.
´ h
12.1945
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
_
with larger positive estimates.
Keystrokes
Display
1000
v 1100
1,100
Two larger, positive estimates.
´_A
Error 8
No root found.