+# During the interpolation, if no value is available over a node, a default value
+# is set: -9999. It has no importance for the final computation, but if the field
+# or the mesh is displayed, it makes huge gap. To prevent this artefact, a more
+# convenient "undefined" value is set. This new undefinde value is given by the user.
+#
+# zUndefThreshold: the default value is -9000. It is tied with the value -9999. given
+# by the interpolation when no value is defined.
+#
+ zUndefThreshold = -9000.
+ if verbose:
+ print "zUndefThreshold: %f" % zUndefThreshold#