Hioki MR8827, Instruction Manual

Page: 240 / 436

235
Waveform Calculation Operators and Results
b
i
: ith member of calculation result data, d
i
: ith member of source channel data
Waveform calculation
type
Description
First derivative (DIF)
Second derivative
(DIF2)
The first and second derivative calculations use a fifth-order Lagrange interpolation
polynomial to obtain a point data value from five sequential points.
d
1
to
d
n
are the derivatives calculated for sample times
t
1
to
t
n
.
Note: Scattering of calculation results increases when a slowly changing waveform is
differentiated.
If scattering is excessive, try to increase the value of the second parameter of the
function.
Refer to “Using the MOV, SLI, DIF and DIF2 operators in an equation (The
second parameter)” (p. 230).
The following equations are the cases where the value of the second parameter
is 1.
Formulas for the first derivative
Point
t
1
b
1
= (−25
d
1
+ 48
d
2
− 36
d
3
+ 16
d
4
− 3
d
5
)/ 12
h
Point t
2
b
2
= (−3 d
1
− 10 d
2
+ 18 d
3
− 6 d
4
+ d
5
)/ 12 h
Point
t
3
b
3
= (
d
1
− 8
d
2
+ 8
d
4
−
d
5
)/ 12
h
↓
Point
t
i
b
i
= (
d
i−2
− 8
d
i−1
+ 8
d
i+1
−
d
i+2
)/ 12
h
↓
Point
t
n−2
b
n−2
= (
d
n−4
− 8
d
n−3
+ 8
d
n−1
−
d
n
)/12
h
Point t
n−1
b
n−1
= ( −d
n−4
+ 6 d
n−3
− 18 d
n−2
+ 10 d
n−1
+ 3 d
n
)/12 h
Point
t
n
b
n
= (3
d
n−4
− 16
d
n−3
+ 36
d
n−2
− 48
d
n−1
+ 25
d
n
)/12
h
b
1
to
b
n
: calculation results
h = Δ t: Sampling Period
Formulas for the second derivative
Point
t
1
b
1
= (35
d
1
− 104
d
2
+ 114
d
3
− 56
d
4
+ 11
d
5
)/12
h 2
Point t
2
b
2
= (11 d
1
− 20 d
2
+ 6 d
3
+ 4 d
4
− d
5
)/12 h
2
Point
t
3
b
3
= (−
d
1
+ 16
d
2
−30
d
3
+ 16
d
4
−
d
5
)/12
h 2
↓
Point
t
i
b
i
= (−
d
i−2
+ 16
d
i−1
− 30
d
i
+ 16
d
i+1
− d
i+2
)/12
h 2
↓
Point
t
n−2
b
n−2
= (−
d
n−4
+ 16
d
n−3
− 30
d
n−2
+ 16
d
n−1
−
d
n
)/12
h 2
Point t
n−1
b
n−1
= (− d
n−4
+ 4 d
n−3
+ 6 d
n−2
− 20 d
n−1
+ 11 d
n
)/12 h
2
Point
t
n
b
n
= (11−
d
n−4
−56
d
n−3
+ 114
d
n−2
− 104
d
n−1
+ 35
d
n
)/12
h 2
11
W
aveform Calculation Functions