Create a bi-orthogonal grid

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Description

Function to create a biorthogonal grid using the thin-plate solution; the grid object created can be used with the draw function to plot the grid.

Usage

1
bgrid(start, xmat, coef, xlimt, iter.limit = 10, perpc = 8)

Arguments

start

coordinates of the starting point to create the grid - usually near the center of region

xmat

n x 2 matrix containing xy coordinates of locations

coef

coefficients of the thin-plate solution, for instance as returned by sinterp

xlimt

vector of 4 elements, representing x- and y-ranges for the grid to be created; if not provided, the ranges of xmat are used.

iter.limit

limit of iterations

perpc

parameter to control spacing of the grid

Value

A list with following named components:

grid

coordinates of points in the grid

ngrid

number of points in the grid

fldmag

the “gradient” index (see Sampson and Guttorp, 1992, for details)

nn

internally set for the maximum number of grid points allowed

References

Sampson P.D., and Guttorp, P., "Nonparametric estimation of nonstationary spatial covariance structure", in Journal of the American Statistical Association, vol 87, pp 108-119, 1992.

See Also

draw, sinterp