observed
exposure levels of all samples; second is the GPS at the observed exposure
levels. The rows are in ascending order for the first column.</p></dd>


<dt>y_obs_ord</dt>
<dd><p>A vector of observed outcome values. The vector is ordered
as <code>obs_ord</code>.</p></dd>


<dt>kernel_fn</dt>
<dd><p>The covariance function of the GP.</p></dd>


<dt>n_neighbor</dt>
<dd><p>The number of nearest neighbors on one side.</p></dd>


<dt>block_size</dt>
<dd><p>Number of samples included in a computation block.
M