Several operations on the characteristic mesh require
the indices of particular (selected) nodes.
The following functions handle the book-keeping for
a list of "selected" nodes.
Procedures which do the actual computations can then
get their node identifiers from this list.
It is intended that these procedures be invoked from
the menu system.
No error trapping is done; be careful.
proc nodelist_AddNode { nid } {
proc nodelist_Clear {} {
proc nodelist_GetNodeId { {i 0} {list_action keep} } {
proc nodelist_DeleteNode {} {
proc nodelist_InteriorNode {} {
proc nodelist_InsertNodeHalfway {} {
proc nodelist_WallNode { Ctype iw } {
proc nodelist_FreeBndyNode { Ctype } {
proc nodelist_ExtendStreamline {} {
proc nodelist_ExtendStreamlineShepard {} {
proc nodelist_MarchAlongCharacteristic { Ctype direction } {