Casio CFX-9800G-w Owners Manual - Page 58

d/d71, 3,gX-1'5

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3 Chapter Differential, Integration, and E Calculations II 3.1 How the Unit Calculates Differentials The following is the input format for differentials: EM Elf(x)MalAxID Increase/decrease of x Point for which you want to determine the derivative tildx(f(x), a, Ax) f(a) The differentiation for this type of calculation is defined as: f(a)=Iim f(a+ Ax)-f(a) Ax-t0 Ax In this definition, infinitesimal is replaced by a sufficiently small Ax, with the value in the neighborhood of f (a) calculated as: f(a + Ax)- f(a) (a)= Ax In order to provide the best precision possible, this unit employs central difference to perform differential calculations. The following illustrates central difference. AY Ax f(a + Ax)-f(a- Ax) 2Ax y=f(x) Vy vx a- Ax a a+Ax The slopes of point a and point a+ Ax, and of point a and point a - Ax in function y=f(x) are as follows: f(a + Ax)- f(a) _ Ay f(a)-f(a- Ax) _ Vy Ax Ax Ax Vx - 80 - In the above, Ay/Ax is called the forward difference, while. Vy/Vx is the backward difference. To calculate derivatives, the unit takes the average between the value of Ay/Axand Vyl,Vx, thereby providinghigher precision for derivatives. This average, which is called the central difference, is expressed as: no _1 (f(a+ ox)-f(a) f(a)-f(a- Ax)) Ax _f(a+ Ax)-f(a- Ax) 2A.Y •To Perform a Differential Calculation Example To determine the derivative at point x=3 for the function y= x3 + 4x2 + x-6, when the increase/decrease of xis: defined as dx= s -5. Input the function f(x). 123 uzenEEMEMEI r dX XA3+4X 2+X- 1 Input point x= a for whiCh you want to determine the derivative. Nclx

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Chapter
3
II
Differential,
Integration,
and
E
Calculations
3.1
How
the Unit
Calculates
Differentials
The
following
is
the
input
format
for
differentials:
Elf(x)MalAxID
Increase/decrease
of
x
Point
for
which
you
want
to
determine
the
derivative
tildx(f(x),
a,
Ax)
f(a)
The
differentiation
for
this
type
of
calculation
is
defined
as:
EM
f(a)=Iim
f(a+
Ax)—f(a)
Ax
—t0
Ax
In
this
definition,
infinitesimal
is
replaced
by
a
sufficiently
small
Ax,
with
the
value
in
the
neighborhood
of
f
(a)
calculated
as:
(a)=
f(a
+
Ax)—
f(a)
Ax
In
order
to
provide
the
best
precision
possible,
this
unit
employs
central
difference
to
per-
form
differential
calculations.
The
following
illustrates
central
difference.
AY
y=
f(x)
Ax
f(a
+
Ax)—f(a—
Ax)
2Ax
Vy
vx
a—
Ax
a
a+Ax
The
slopes
of
point
a
and
point
a+
Ax,
and
of
point
a
and
point
a
Ax
in
function
y=f(x)
are
as
follows:
f(a
+
Ax)—
f(a)
_
Ay
f(a)—f(a-
Ax)
_
Vy
Ax
Ax
Ax
Vx
In
the
above,
Ay/Ax
is
called
the
forward
difference,
while.
Vy/Vx
is
the
backward
difference.
To
calculate
derivatives,
the
unit
takes
the
average
between
the
value
of
Ay/Axand
Vyl,Vx,
thereby
providing
higher
precision
for
derivatives.
This
average,
which
is
called
the
central
difference,
is
expressed
as:
no
_1
(f(a+
ox)-f(a)
f(a)-f(a—
Ax))
Ax
_f(a+
Ax)—f(a-
Ax)
2A.Y
•To
Perform
a
Differential
Calculation
To
determine
the
derivative
at
point
x=3
for
the
function
y=
x
3
+
4x
2
+
x-6,
when
the
increase/decrease
of
xis:
defined
as
dx=
s
—5.
Example
Input
the
function
f(x).
123
uzenEEMEMEI
Input
point
x=
a
for
whiCh
you
want
to
determine
the
derivative.
Input
Ax,
which
is
the
increase/
decrease
of
x.
CIODMITI
r
dX
X
A
3+4X
2
+X
- 1
N
clx<X"3+4X
2
+X
- 1
I
d/d71
,3,gX-1‘5_
+4X 2+X-1
r5
rX
2
+X
- 6
)
52
•X
is
the
only
expression
that
can
be
used
in
the
function
fi
x).
If
you
use
any
other
varia-
ble
name
(A
through
Z,
r,
or
0),
that
variable
name
is
regarded
as
a
constant,
using
the
current
contents
of
the
corresponding
value
memory
in
the
calculation.
*Input
of
Ax
for
the
increase/decrease
of
x
can
be
skipped.
When
you
do,
the
unit
auto-
matically
uses
a
value
for
Ax
that
is
appropriate
for
the
value
of
x=
a,
which
you
speci-
fied
as
the
point
for
which
you
wanted
to
determine
the
derivative.
•In
general,
calculation
precision
is
±1
at
the
least
significant
digit
of
the
result.
80
-
81