HP 33s scientific calculator 用户手册
More about Solving
D–13
File name 33s-English-Manual-040130-Publication(Edition 2).doc Page : 388
Printed Date : 2004/1/30 Size : 13.7 x 21.2 cm
Printed Date : 2004/1/30 Size : 13.7 x 21.2 cm
Checksum and length: B956 75
You can subsequently delete line J0003 to save memory.
Solve for X using initial guesses of 10
–8
and –10
–8
.
Keys:
(In RPN mode)
Display: Description:
}
8
z
e
X
1
z
}
8
z
_
Enters guesses.
º
s
J
Selects program "J" as the
function.
function.
Û
X
Solves for X; displays the result.
Round–Off Error
The limited (12–digit) precision of the calculator can cause errors due to rounding
off, which adversely affect the iterative solutions of SOLVE and integration. For
example,
off, which adversely affect the iterative solutions of SOLVE and integration. For
example,
0
10
-
]
10
1)
x
[(
30
2
15
=
+
+
has no roots because f(x) is always greater than zero. However, given initial
guesses of 1 and 2, SOLVE returns the answer 1.0000 due to round–off error.
guesses of 1 and 2, SOLVE returns the answer 1.0000 due to round–off error.
Round–off error can also cause SOLVE to fail to find a root. The equation
0
7
-
x
2
=
has a root at
7
. However, no 12–digit number exactly equals
7
, so the
calculator can never make the function equal to zero. Furthermore, the function
never changes sign SOLVE returns the message . However, the final
estimate of x (press
never changes sign SOLVE returns the message . However, the final
estimate of x (press
~
to see it) is the best possible 12–digit approximation of
the root when the routine quits.