Sharp PC-1500 Applications Manual page 11

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PROGRAM
TITLE
SHARP
ROOT OF AN EQUATION
[ Outline
I
(Mathematics)
PROGRAM NO.
PS - A- I
Finding the root of
an
equation is generally a time consuming task . Herc is a
method of root approximation using Newton 's Method.
When
a
root is found , the starting point automatic.ally varies with the designated
interval according to Newton's Method.
A
quadratic equation has been chosen as
an example:
[ Operating Guide
I
Input : Starting point
Minute value
Interval
y
I
~
'1Gf"'
X >; :x;
:-.: Interval
Starting Point
©
@
©
® ® - Section No.
Output : Root value (Press the I
ENTER
I key to find a root for the next interval.)
[Example
I
x
3
-
2x
2
-
x
+
2 = O {Root = - 1, 1, 2)
Calculation is made with the starting point being
0,
the minute value being
Io- •
and the interval bei ng 0.5 .
Write a function as a subroutine after line 500.
How to write a subroutine (in the above example):
I. Set the "PRO" mode by pressing the
~
key.
2. SOOD =
((x -
2)
*
x -
I)
*
x
+ 2 l
ENTER
I
5 10 RETURN I
ENTER
f
[Contents
I (
Formula)
, f
( Xn )
X. , 1= Xn - j ' ( Xn )
When the absolute value of the difference between Xn and
Xn+I
becomes less
than 10-
8 ,
Xn is displayed as a root. The differential
r(x)
is defined as follows:
f,
(x)
=
f (
x
+
h ) -
f (
x )
h
(h: min ute value)
To vary 10- s, change IE- 8 of the 340 line.
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