Computes the gradient of the covariance vector
c(x) computed by
covMat1Mat2 with respect to
x, for a given covariance structure.
covVector.dx(object, x, X, c)
an object specifying the covariance structure.
a vector representing the specific location.
a matrix whose columns represent locations.
a vector containing the covariances between the location
x and the set of locations specified in
A vector of real numbers equal to the gradient of
c as a function of