apunkt/GPy
1
0
Fork 0
mirror of https://github.com/SheffieldML/GPy.git synced 2026-05-21 14:05:14 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions

[SSGPLVM] numerical stability

Browse source
This commit is contained in:
Zhenwen Dai 2014-03-04 12:06:41 +00:00
parent 5c82fe39b9
commit 0f37cc721b
3 changed files with 7 additions and 5 deletions
Download patch file Download diff file Expand all files Collapse all files

6
GPy/kern/_src/rbf_psi_comp/ssrbf_psi_comp.py
View file

@ -42,7 +42,8 @@ def _psi1computations(variance, lengthscale, Z, mu, S, gamma):
_psi1_common = gamma[:,None,:] / (lengthscale2*_psi1_denom*_psi1_denom_sqrt) #Nx1xQ
_psi1_exponent1 = np.log(gamma[:,None,:]) -0.5 * (_psi1_dist_sq + np.log(_psi1_denom)) # NxMxQ
_psi1_exponent2 = np.log(1.-gamma[:,None,:]) -0.5 * (np.square(Z[None,:,:])/lengthscale2) # NxMxQ
_psi1_exponent = np.log(np.exp(_psi1_exponent1) + np.exp(_psi1_exponent2)) #NxMxQ
_psi1_exponent_max = np.maximum(_psi1_exponent1,_psi1_exponent2)
_psi1_exponent = _psi1_exponent_max+np.log(np.exp(_psi1_exponent1-_psi1_exponent_max) + np.exp(_psi1_exponent2-_psi1_exponent_max)) #NxMxQ
_psi1_exp_sum = _psi1_exponent.sum(axis=-1) #NxM
_psi1_exp_dist_sq = np.exp(-0.5*_psi1_dist_sq) # NxMxQ
_psi1_exp_Z = np.exp(-0.5*np.square(Z[None,:,:])/lengthscale2) # 1xMxQ
@ -89,7 +90,8 @@ def _psi2computations(variance, lengthscale, Z, mu, S, gamma):
_psi2_common = gamma[:,None,None,:]/(lengthscale2 * _psi2_denom * _psi2_denom_sqrt) # Nx1x1xQ
_psi2_exponent1 = -_psi2_Zdist_sq -_psi2_mudist_sq -0.5*np.log(_psi2_denom)+np.log(gamma[:,None,None,:]) #N,M,M,Q
_psi2_exponent2 = np.log(1.-gamma[:,None,None,:]) - 0.5*(_psi2_Z_sq_sum) # NxMxMxQ
_psi2_exponent = np.log(np.exp(_psi2_exponent1) + np.exp(_psi2_exponent2))
_psi2_exponent_max = np.maximum(_psi2_exponent1, _psi2_exponent2)
_psi2_exponent = _psi2_exponent_max+np.log(np.exp(_psi2_exponent1-_psi2_exponent_max) + np.exp(_psi2_exponent2-_psi2_exponent_max))
_psi2_exp_sum = _psi2_exponent.sum(axis=-1) #NxM
_psi2_q = np.square(variance) * np.exp(_psi2_exp_sum[:,:,:,None]-_psi2_exponent) # NxMxMxQ
_psi2_exp_dist_sq = np.exp(-_psi2_Zdist_sq -_psi2_mudist_sq) # NxMxMxQ