HP HP-15C, Owner'S Handbook Manual

Page: 202 / 288

202 Section 14: Numerical Integration
If the uncertainty of an approximation is larger than what you choose to
tolerate, you can decrease it by specifying a greater number of digits in the
display format and repeating the approximation.
*
Whenever you want to repeat an approximation, you don't need to key the
limits of integration back into the X- and Y-registers. After an integral is
calculated, not only are the approximation and its uncertainty placed in the
X- and Y-registers, but in addition the upper limit of integration is placed in
the Z-register, and the lower limit is placed in the T-register. To return the
limits to the X- and Y-registers for calculating an integral again, simply
press
) )
.
Example: For the integral in the expression for J
1
(l), you want an answer
accurate to four decimal places instead of only two.
Keystrokes Display
´ i
4
1.8826 -03
Set display format to
i
4.
)) 3.1416 00
Roll down stack until upper
limit appears in X-register.
´f
1
1.3825 00
Integral approximated in
i
4.
®
1.7091 -05
Uncertainty of
i
4 approximation.
The uncertainty indicates that this approximation is accurate to at least four
decimal places. Note that the uncertainty of the
i
4 approximation is
about one-hundredth as large as the uncertainty of the
i
2
approximation. In general, the uncertainty of any
f
approximation
decreases by about a factor of 10 for each additional digit specified in the
display format.
*
Provided that f(x) is still calculated accurately to the number of digits shown in the display.