f:X→Y ∀x∈X, x → y(x)∈Y
y(x) = (x2 − 4) (2x).
X N −3 3
→
→
→
y = −wx y x w
y = −wx + b
→
→
→
→
→ ←
add label=‘best-fit’
–
error:
not the best-fit, the true function
w w = −5.0
→
w1
∂L = 1 ∂ (w1xn−yn)2 = 2 xn(w1xn−yn)= 2(w1⊤−⊤),
∂w1 Nn∂w1 Nn N
(xn,yn) n = 1,…,N
→
→
w0 w1
→
x·y−x·y w1= 22 .
x−x
· z = 1 N zn.
0= ∂L = 1 ∂ (w0+w1xn−yn)2, i=0,1.
N n=1
∂wi N n ∂wi
x t
w 0 = y − w 1 x .
→