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OPIUM.py
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OPIUM.py
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# -*- coding: utf-8 -*-
"""
Greville and OPIUM method from:
J. Tapson and A. van Schaik,
"Learning the Pseudoinverse Solution to Network Weights"
Neural Networks
Created on Sun Aug 5 10:05:29 2012
@author: andrevanschaik
"""
from numpy import dot, exp, eye, sqrt
def OPIUM(x,ee,M,P): #basic OPIUM
psi = dot(P,x)
nrm1 = 1+dot(x.T,psi)
P -= dot(psi,psi.T)/nrm1
M += dot(ee,psi.T)/nrm1
def OPIUMl(x,ee,M,g): #OPIUM light
nrm1 = (1.0/g)+dot(x.T,x)
M += dot(ee,x.T)/nrm1
def OPIUMd(x,ee,M,P,alpha): #dynamic OPIUM
psi = dot(P,x)
nrm1 = 1+dot(x.T,psi)
nrm2 = 1+alpha*(1-exp(-sqrt(dot(ee.T,ee))/ee.size))
P -= dot(psi,psi.T)/nrm1
P += alpha * eye(P.size**0.5) * (1-exp(-sqrt(dot(ee.T,ee))/ee.size))
P /= nrm2
M += dot(ee,psi.T)/nrm1