## doc: gp_downdate

Posterior and given

### Syntax

[mu, sigma2] = gp_downdate(Ktt, Yt, i, BayesInv)
[mu, sigma2] = gp_downdate(Ktt, Yt, i, BayesInv, Ht)

### Arguments

*Ktt* kernel matrix *(nt, nt)* between the points of *Xt**Yt* vector *(nt, 1)* of observations*i* indice of removed observation*BayesInv* struct array returned by *gp_inf(Ht, Ktt, Yt, noise)**Ht* matrix *(nt, b)* of basis data as returned by *basis_cst(Xt)*

### Outputs

*mu* scalar *(1,1)* posterior mean *sigma2* scalar *(1,1)* posterior variance

### See also

gp_pred | gp_loolik