1Areas_params(3NCARG)             NCAR GRAPHICS            Areas_params(3NCARG)
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NAME

6       Areas_params - This document briefly describes all Areas parameters.
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DESCRIPTION

9       Areas currently supports nine parameters. These parameters are useful
10       mostly for debugging Areas problems. The current values may be
11       retrieved using one of the routines ARGETI or ARGETR. Parameter values
12       may be reset using the routine ARSETI or ARSETR; the parameter 'DI' is
13       for retrieval only and may not be given a new value by the user.
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15       The Areas parameter descriptions appear below in alphabetical order.
16       Each description begins with a line giving the parameter name and the
17       intrinsic FORTRAN type of the parameter.
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19       'AL' - Real
20              Arrowhead Length.  AL specifies the length of each arrowhead
21              used on a debug plot produced by ARDBPA. The value is
22              interpreted as a fraction of the width of the plotter frame.
23              Using a value which is less than or equal to zero causes
24              arrowheads to be omitted.  The default value is .008.
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26       'AT' - Integer
27              Arithmetic Type flag.  AT allows the user to specify the type of
28              arithmetic Areas is to use or to find out what type it decided
29              to use.  A call to set the value of AT should precede any other
30              call to an Areas routine (except, possibly, one to set the value
31              of LC) and it should only be done once.  A call to get the value
32              of AT will either return the value you set or a value picked by
33              Areas.
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35              < 1  Areas decides what sort of arithmetic to use.
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37                1  Real arithmetic is to be used.
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39                2  Double-precision arithmetic is to be used.
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41                3  Multiple-precision arithmetic is to be used and Areas is to
42                   choose the base value.
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44              > 3  Multiple-precision arithmetic is to be used and AT
45                   specifies the base value.  (For example, the value 100
46                   specifies the use of base-100 multiple-precision integer
47                   arithmetic.)
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49            Default: 0
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51            Note: You should use a nonzero value of AT only on the
52            recommendation of an NCAR consultant.
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54       'AW' - Real
55              Arrowhead Width.  AL specifies the half-width of each arrowhead
56              used on a debug plot produced by ARDBPA. The value is
57              interpreted as a fraction of the width of the plotter frame.
58              Using a value which is less than or equal to zero causes
59              arrowheads to be omitted.  The default value is .002.
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61       'DB' - Integer
62              DeBug-plots flag. DB allows the user to study the area map.
63
64                0  Debugging turned off. This is the default.
65
66              > 0  Debugging is on. At selected break points, ARPRAM produces
67                   plots showing all edge segments in the area map that belong
68                   to the edge group with group identifier DB.
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70       'DC' - Integer
71              Debug Colors index. ARDBPA uses color indices DC+1 through DC+5
72              for debug-plot colors.
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74              By default, DC=100, so ARDBPA defines and uses color indices 101
75              through 105.
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77       'DI' - Integer
78              Direction Indicator flag. The value of DI is for retrieval only
79              and cannot be set by the user.  A value returned for DI is
80              meaningful only when the call to ARGETI that retrieves it
81              originates from the user-written routine (dummy argument "APR")
82              that is called by ARSCAM.  It then gives you information about
83              the area whose polygonal boundary is defined by the values of
84              APR's arguments. The two possible values of DI are:
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86              1    Edge of the area is given in counterclockwise order (with
87                   the interior to the left).
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89              2    Edge of the area is given in clockwise order (with the
90                   interior to the right).
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92
93       'ID' - Real
94              Identifier Distance.  ID specifies the distance from an arrow to
95              a left or right area identifier on a debug plot produced by
96              ARDBPA. The value is interpreted as a fraction of the width of
97              the plotter frame. Using a value which is less than or equal to
98              zero causes area identifiers to be omitted.  The default value
99              is .004.
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101       'IS' - Real
102              Identifier Size.  IS specifies the size of the characters used
103              to write an area identifier on a debug plot produced by ARDBPA.
104              The value is interpreted as a fraction of the width of the
105              plotter frame. Using a value which is less than or equal to zero
106              causes area identifiers to be omitted.  The default value is
107              .001.
108
109       'LC' - Integer
110              Largest Coordinate. LC lets you specify the largest coordinate
111              allowed in an area map. X and Y coordinates in an area map are
112              represented by integers in the range from 0 to LC, inclusive;
113              the default value of LC is 1000000.
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115              The minimum value allowed for LC is 1000; attempting to set
116              LC<1000 gives it the value 1000. The value of LC must not be
117              greater than the largest integer on the machine on which Areas
118              is running; its value must also be exactly representable as a
119              real number on that machine.
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121              A call to set the value of LC should precede any other call to
122              an Areas routine and should only be done once.
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124       'RC' - Integer
125              Reconciling Conflicts in area-identifier information.
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127              This is an array of 16 values, indexed by group identifier.  To
128              set all values in the array to the same value "n", use "CALL
129              ARSETI('RC',n)"; to set just the first value in the array, use
130              "CALL ARSETI('RC(1)',n)"; to set just the second value, use
131              "CALL ARSETI('RC(2)',n)"; and so on.  You can call ARGETI to get
132              the value of RC(1) or RC(2) or RC(3), etc.; if you ask for the
133              value of just RC, you will get the value of RC(1).
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135              RC(1) is associated with edge group 1, RC(2) with edge group 2,
136              and so on.  An edge group with a group identifier greater than
137              16 is associated with RC(16).
138
139              When the set of possible area identifiers for a given area in a
140              given group is contradictory, some algorithm must be used to
141              choose an identifier for the area.  The value of that element of
142              RC that is associated with the group determines what algorithm
143              will be used, as follows:
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145              0    The default scheme: If any of the possible area identifiers
146                   is negative, use -1 as the identifier for the area.
147                   Otherwise, if none of the possible values is non-zero, use
148                   a zero identifier.  Otherwise, from among the non-zero
149                   possibilities, use the one most recently seen by AREAS.
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151              1    The set of possible identifiers is examined:  Zeroes are
152                   ignored, negatives are treated as -1's, and the value that
153                   occurs most frequently in the resulting set is used as the
154                   identifier for the area.
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156              2    Using RC = 2 is just like using RC = 1 except that zeroes
157                   are not ignored: the area identifier used is simply the one
158                   that occurs most frequently in the set of possibilities
159                   (all negatives being treated as -1's).
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161              -1   Using RC = -1 is just like using RC = 1 except that, if
162                   there are any negatives in the set of possible identifiers,
163                   a -1 is used.
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165              -2   Using RC = -2 is just like using RC = 2 except that, if
166                   there are any negatives in the set of possible identifiers,
167                   a -1 is used.
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SEE ALSO

170       Online: argeti, argetr, arseti, arsetr
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172       Hardcopy: NCAR Graphics Contouring and Mapping Tutorial
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175       Copyright (C) 1987-2009
176       University Corporation for Atmospheric Research
177       The use of this Software is governed by a License Agreement.
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181UNIX                              April 1995              Areas_params(3NCARG)
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