matern_spheretime_warp | R Documentation |
From a matrix of longitudes, latitudes, times, and a vector covariance parameters of the form (variance, range_1, range_2, smoothness, nugget, <5 warping parameters>), return the square matrix of all pairwise covariances.
matern_spheretime_warp(covparms, lonlattime)
d_matern_spheretime_warp(covparms, lonlattime)
covparms |
A vector with covariance parameters in the form (variance, range_1, range_2, smoothness, nugget, <5 warping parameters>). range_1 is a spatial range parameter that assumes that the sphere has radius 1 (units are radians). range_2 is a temporal range parameter. |
lonlattime |
A matrix with |
A matrix with n
rows and n
columns, with the i,j entry
containing the covariance between observations at lonlat[i,]
and
lonlat[j,]
.
d_matern_spheretime_warp()
: Derivatives with respect to parameters
The function first calculates the (x,y,z) 3D coordinates, and then "warps"
the locations to (x,y,z) + \Phi(x,y,z)
, where \Phi
is a warping
function composed of gradients of spherical harmonic functions of degree 2.
See Guinness (2019, "Gaussian Process Learning via Fisher Scoring of
Vecchia's Approximation") for details.
The warped locations are input into matern_spacetime
. The function
does not do temporal warping.
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