On entry: the description of the lines that define the boundary domain. The line
i, for
i=1,…,m, is defined as follows:
- LINED1i
- The number of points on the line, including two end points.
- LINED2i
- The first end point of the line. If LINED2i=j, then the co-ordinates of the first end point are those stored in COORCH:j.
- LINED3i
- The second end point of the line. If LINED3i=k, then the co-ordinates of the second end point are those stored in COORCH:k.
- LINED4i
- This defines the type of line segment connecting the end points. Additional information is conveyed by the numerical value of LINED4i as follows:
| (i) |
LINED4i>0, the line is described in FBND with LINED4i as the index. In this case, the line must be described in the trigonometric (anticlockwise) direction; |
| (ii) |
LINED4i=0, the line is a straight line; |
| (iii) |
if LINED4i<0, say
(-p),
then the line is a polygonal arc joining the end points and interior points specified in CRUS. In this case the line contains the points whose co-ordinates are stored in
COORCH:j
,
CRUS:p
,
CRUS:p+1
,…,
CRUS:p+r-3
,
COORCH:k, where
r=LINED1i,
j=LINED2i and
k=LINED3i. |
Constraints:
- 2≤LINED1i;
- 1≤LINED2i≤NLINES;
- 1≤LINED3i≤NLINES;
- LINED2i≠LINED3i, for i=1,2,…,NLINES.
For each line described by
FBND (lines with
LINED4i
>
0
, for
i=1,2,…,NLINES) the two end points (
LINED2i
and
LINED3i
) lie on the curve defined by index
LINED4i in
FBND, i.e.,
FBND
LINED4i,COORCH1LINED2i,COORCH2LINED2i,RUSER,IUSER
=
0
;
FBND
LINED4i,COORCH1LINED3i,COORCH2LINED3i,RUSER,IUSER
=
0
, for i=1,2,…,NLINES.
For all lines described as polygonal arcs (lines with
LINED4i
<
0
, for
i=1,2,…,NLINES) the sets of intermediate points (i.e.,
-LINED4i
:
-LINED4i
+
LINED1i
-
3
for all
i such that
LINED4i<0) are not overlapping. This can be expressed as:
or
for a
j such that
j=1,2,…,NLINES,
j≠i and
LINED4j<0.
