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The HMC Algorithm with Overrelaxation and Adaptive--Step ...

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1.9<br />

1.7<br />

1.5<br />

1.3<br />

1.1<br />

0.9<br />

0.7<br />

0.5<br />

Background<br />

Aim of Talk<br />

<strong>The</strong> Hamiltonian Monte Carlo (<strong>HMC</strong>) <strong>Algorithm</strong><br />

Improving Performance of <strong>HMC</strong> <strong>Algorithm</strong><br />

Numerical Experiments & Results<br />

Comparing O<strong>HMC</strong> vs <strong>HMC</strong><br />

Example results from the improved <strong>HMC</strong> algorithm<br />

Gaussian Target<br />

1<br />

π(x) = exp ( − 1 (2π) n/2 |Σ| 1/2 2 xT Σ −1 x )<br />

Σ = I<br />

Results (n=64, N=2000)<br />

O<strong>HMC</strong> <strong>HMC</strong> Ideal<br />

Accept. rate 0.99 0.99 1<br />

P(0) 1.35 1.51 1<br />

κ ∗ 1.65 1.45<br />

CPU time[sec] 561.22 557.38<br />

E 0.74 0.66 1<br />

r 6.7e − 4 7.6e − 4 < 0.01<br />

τ int 1.63 1.85 0.5<br />

N eff 614 542 2000<br />

Graphical Illustration<br />

P(κ)<br />

ρ int<br />

(τ)<br />

3.1623<br />

2.5119<br />

1.9953<br />

1.5849<br />

1.2589<br />

1<br />

0.7943<br />

0.631<br />

0.5012<br />

0.3981<br />

0.3162<br />

10 −3 10 −2 10 −1 10 0 10 1<br />

κ<br />

O<strong>HMC</strong><br />

<strong>HMC</strong><br />

0.3<br />

0 2 4 6 8 10 12 14 16<br />

τ<br />

iacf O<strong>HMC</strong><br />

(τ*,τ* int<br />

) O<strong>HMC</strong><br />

iacf <strong>HMC</strong><br />

(τ*,τ* int<br />

) <strong>HMC</strong><br />

M. Alfaki, S. Subbey, <strong>and</strong> D. Haugl<strong>and</strong> <strong>The</strong> Hamiltonian Monte Carlo (<strong>HMC</strong>) <strong>Algorithm</strong>

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