'Momenturm BP'에 해당되는 글 1

  1. 2009/01/15 모멘텀 BP 알고리즘 momentum BP algorithm
 

모멘텀 BP 알고리즘 momentum BP algorithm

신경망 | 2009/01/15 17:54 | Posted by DMW
크리에이티브 커먼즈 라이선스
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Step 1. Initialize weights and count
  v, w <- small random number
  p <- number of traning pattern pairs
  k <- 1
  E <- 0
Initialize temporary weight variation
  temp_w <- 0
  temp_v <- 0

Step 2. Set learning rate(a) and Emax α(>0)
Set momentum constant β(0 < β < 0.8)

Step 3. For each traning pattern pair (X, D)
do step 4 - 9 until k = p

Step 4. compute output
NET_z = Xk inner_product Vk
Z = f(NET_z)

f(NET_z) = 1 / (1 + exp(-NET_z))                                    ; unipolar sigmoid
                (1 - exp(-NET_z)) / (1 + exp(-NET_z))           ; bipolar sigmoid

NET_y = Z inner_product Wt
Y = f(NET_y)

f(NET_y) = 1 / (1 + exp(-NET_y))                                    ; unipolar sigmoid
                (1 - exp(-NET_y)) / (1 + exp(-NET_y))           ; bipolar sigmoid

Step 5. Compute output error
E <- 0.5 * (Dk - Yk)^2 + E

Step 6. Compute error signal
delta_y = (d-y) * y * (1 - y)                             ; unipolar sigmoid
              0.5 * (d-y) * (1-y^2)                         ; bipolar sigmoid

delta_z = z * (1-z) * sumation of delta_y*W      ; unipolar sigmoid
             0.5 * (1-z^2) * sumation of delta_y*W ; bipolar sigmoid

Setp 7. Update weights
Wk+1 = Wk + ΔWk
        = Wk + a * δy * Zk + βΔWk-1

Vk+1 = Vk + ΔVk
       = Vk + a * δz * Xk + βΔVk-1

Step 8. Save weight variation
temp_w <- Δwk
temp_v <- Δvk


Step 9. Increase counter and goto Step 3
k <- k + 1
 
Step 10. Test stop condition
If E < Emax, stop
else E <- 0, goto Step 3

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