Mitutoyo SJ-301 - Kurtosis of the Profile, Ku

14 - 23 No. 99MBB091A
14. REFERENCE INFORMATION
14.5.11 Kurtosis of the profile, Ku
Ku represents the degree of concentration around the mean line of an amplitude distribution
curve. The kurtosis of a profile, Ku, is given by the following formula.
Ku is large.
Ku is small.
Triangular wave Sine wave Square wave
Ku=1.5Ku=1.79 Ku=1
u=
n
i=1
Yi
∑
Rq
4
1
n
1
•
4
*1: Refer to section 14.5.21, “Profile height amplitude curve, ADC”.
14.5.12 Arithmetic mean slope of the profile, Δa
Δa is the arithmetic mean of the absolute values of the local slope of the profile. The local
slope of the profile dz/dx is given by the following formula.
= ( zi+3 – 9 zi+2 + 45 zi+1 – 45 zi-1 + 9 zi-2 - zi+3 )
dzi
dxi
1
60x
(Where, the zi is the height of the i’th point and the Δx is the distance to the adjacent data
point.)
14.5.13 Root-mean-square slope of the profile, Δq
Δq is the square root of arithmetic mean of the squares of the local slope dz/dx of the profile.