theorem
for
a,
b,
c,
d being
Real for
f,
F being
Function of
REAL,
REAL st
b > 0 &
c > 0 &
d > 0 & ( for
x being
Real holds
f . x = max (
0,
(b - |.((b * (x - a)) / c).|)) ) & ( for
x being
Real holds
F . x = min (
d,
(max (0,(b - |.((b * (x - a)) / c).|)))) ) holds
centroid (
f,
['(a - c),(a + c)'])
= centroid (
F,
['(a - c),(a + c)'])