## ../source/moc_unitproc.c

\file moc_unitproc.c * \ingroup imoc * \brief Basic Unit Processes. * * Basic unit processes implemented in C. * Each function computes the data for a new node based on information * from other nodes. * The functions are computationally intensive and access the internals of * the node data structure directly. * Thus, we believe that the implementation is faster and tidier than a pure * Tcl implementation -- at least we hope so.

Most of these functions involve some iteration. The parameters for convergence check are:
max_iteration = 15
position_tolerance = 1.0e-5

``` int InteriorNode( int node1, int node2, int node4 ) ```

Purpose: Calculate an interior point from two initial points.
Input :
node1 : index of initial point along C- characteristic
node2 : index of initial point along C+ characteristic
node4 : index of solution point (may have a value of -1)
If -1 is specified as the index for node4, a new node will be created for the solution point.
Output :
Returns the index of the solution point or a value of -1 if there has been a failure.
(Available from the Tcl interpreter.)

``` int InsertNode( int node1, int node2, int node4, double alpha ) ```

Purpose: Insert a node (node4) in between two initial nodes (node1 and node2).
If node1 and node2 are adjacent nodes along a characteristic line, node4 will be connected in between.
Input :
node1 : index of initial point 1
node2 : index of initial point 2
node4 : index of solution point (may have a value of -1)
If -1 is specified as the index for node4, a new node will be created for the solution point.
alpha : fraction that node4 is like node2; n4.value = alpha n2.value + (1-alpha) n1.value
Output :
Returns the index of the solution point or a value of -1 if there has been a failure.
(Available from the Tcl interpreter.)

``` int CMinusWallNode( int iw, int node1, int node4 ) ```

Purpose: Calculate a wall point from one initial (C-) point.
Input :
iw : Index of selected wall.
node1 : index of initial point along C- characteristic
node4 : index of solution point (may have a value of -1)
If -1 is specified as the index for node4, a new node will be created for the solution point.
Output :
Returns the index of the solution point or a value of -1 if there has been a failure.
(Available from the Tcl interpreter.)

``` int CPlusWallNode( int iw, int node2, int node4 ) ```

Purpose: Calculate a wall point from one upstream (C+) point.
Input :
iw : index of the wall
node2 : index of initial point along C+ characteristic
node4 : index of solution point (may have a value of -1)
If -1 is specified as the index for node4, a new node will be created for the solution point.
Output :
Returns the index of the solution point or a value of -1 if there has been a failure.
(Available from the Tcl interpreter.)

``` int CPlusFreeBndyNode( int node0, int node2, int node4 ) ```

Purpose: Calculate a free-boundary point from one point (node0) already on the boundary and one point (node2) on a C+ characteristic.
Input :
node0 : index of initial point along C0 streamline
node2 : index of initial point along C+ characteristic
node4 : index of solution point (may have a value of -1)
If -1 is specified as the index for node4, a new node will be created for the solution point.
Output :
Returns the index of the solution point or a value of -1 if there has been a failure.
(Available from the Tcl interpreter.)

``` int CMinusFreeBndyNode( int node0, int node1, int node4 ) ```

Purpose: Calculate a free-boundary point from one point (node0) already on the boundary and one point (node1) on a C- characteristic.
Input :
node0 : index of initial point along C0 streamline
node1 : index of initial point along C- characteristic
node4 : index of solution point (may have a value of -1)
If -1 is specified as the index for node4, a new node will be created for the solution point.
Output :
Returns the index of the solution point or a value of -1 if there has been a failure.
(Available from the Tcl interpreter.)

``` int AddStreamNode( int node0, int node1, int node2, int node4, int test_only ) ```

Purpose: Calculate a new streamline node, extending the streamline to the line joining nodeA and nodeB.
Input :
node0 : index of initial point on the streamline
node1 : index of first initial interpolation point
node2 : index of second initial interpolation point
node4 : index of solution point (may have a value of -1)
If -1 is specified as the index for node4, a new node will be created for the solution point.
test_only : flag to indicate whether we want to test for intersection only or if we actually want to add the node to the streamline
test_only == 0 : add the node
test_only == 1 : test for intersection only
Output :
if test_only == 0 : returns the index of the solution point or a value of 0 if there has been a failure.
if test_only == 1 : returns 1 if intersection occurred between nodes 1 and 2. A value of 0 indicates that intersection did not occur between nodes 1 and 2.
(Available from the Tcl interpreter.)

``` int StepStreamNode( int node0, int node4, double dL ) ```

Purpose: Calculate a new streamline node, extending the streamline by length dL
Input :
node0 : index of initial point on the streamline
node4 : index of solution point (may have a value of -1)
dL : step-size along streamline; A positive value will step downstream while a negative value will step upstream.
If -1 is specified as the index for node4, a new node will be created for the solution point.
Output :
Returns the index of the solution point or a value of -1 if there has been a failure. One possible failure is that there are no nodes close enough to include in the interpolation phase.
(Available from the Tcl interpreter.)

``` int InterpolateNode( double x_point, double y_point, double R, int node4 ) ```

Purpose: Locate a new node at coordinates (x,y), interpolating the node's properties from other near-by nodes.
Input :
x_point, y_point : coordinates of the new node
R : radius-of-influence for the Shepard interpolation
node4 : index of solution point (may have a value of -1)
If -1 is specified as the index for node4, a new node will be created for the solution point.
Output :
Returns the index of the solution point or a value of -1 if there has been a failure. One possible failure is that there are no nodes close enough to include in the interpolation.
(Available from the Tcl interpreter.)

Extracted by docgen.awk Mon Aug 09 23:28:59 EST 2004