Casio CLASSPAD 330 3.04 User Manual
Page 171
20060301
2-8-11
Using the Action Menu
S FFT, IFFT
Function:
“
FFT
”
is the command for the fast Fourier Transform, and
“
IFFT
”
is the
command for the inverse fast Fourier Transform.
2
n
data values are needed to perform FFT and IFFT. On the ClassPad, FFT and IFFT are
calculated numerically.
Syntax: FFT( list ) or FFT( list,
m
)
IFFT( list ) or IFFT( list,
m
)
• Data size must be 2
n
for
n
= 1, 2, 3, ...
• The value for
m
is optional. It can be from 0 to 2, indicating the FFT parameter to use.
m
= 0 Signal Processing
m
= 1 Pure Math
m
= 2 Data Analysis
The Fourier Transform is defined as the following:
Some authors (especially physicists) prefer to write the transform in terms of angular
frequency
W
N instead of the oscillation frequency N.
However, this destroys the symmetry, resulting in the transform pair shown below.
–
F
(
k
)
e
2
ikx
dk
f
(
x
)
=
–
f
(
x
)
e
–2
ikx
dx
F
(
k
)
=
–
h
(
t
)
e
–
i
t
dt
H
(
)
=
F
[
h
(
t
)]
=
–
H
(
)
e
i
t
d
h
(
t
)
=
F
–1
[
H
(
)]
=
1
2
–
f
(
t
)
e
–
iyt
dt
g
(
y
)
=
F
[
f
(
t
)]
=
1
2
–
g
(
y
)
e
iyt
dy
f
(
t
)
=
F
–1
[
g
(
y
)]
=
1
2
To restore the symmetry of the transforms, the convention shown below is sometimes
used.