On exit:
contains the value of the partial derivatives with respect to the
th independent variable (dimension) of the interpolant
at
, for
, and for each of the partial derivatives
. If any of these evaluation points lie outside the region of definition of the interpolant, the corresponding entries in
qx are set to extrapolated approximations to the partial derivatives, and
nag_nd_shep_eval (e01znc) returns with
NE_BAD_POINT.