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 X (see covMat1Mat2).
A vector of real numbers equal to the gradient of c as a function of x.