
1-11Soft Sensors
hidden unit, and the connections between the units carry weights. e role of the hidden units
is to collect the signals at their input, that is, the outputs of the preceding layer; multiply them by
th
e
co
nnection
we
ights;
bu
ild
a su
m
of th
em;
an
d
pr
ocess
th
em
usi
ng
th
e
tr
ansfer
fu
nction
g
hidden
:
x g w x
i
j
j i j
hidden hidden hidden in
=
∑
,
(1.18
)
where
x
out
is the output of the MLP
w
is the weight between the ith hidden unit and the output unit
g
out
() is the transfer function of the output neuron
A
re
markable
th
eoretical
pr
operty
of th
e
ML
P
is th
at
th
ey
ar
e
un
iversal
fu
nction
ap
proximators,
wh
ich
me
ans
th
at
pr
ovided
en
oug ...