NAME

       CONOP3 - sets option switches and specifys various REAL parameters to be used by the
       Conran_family utility.

SYNOPSIS

       CALL CONOP3 (IOPT, ARRAY, LENA)

DESCRIPTION

       IOPT        Character, input -- Selects an internal parameter and sets an option switch.
                   The possibilities are:

                    'CHL=ON' or 'CHL=OFF'
                    'CIL=ON' or 'CIL=OFF'
                    'CON=ON' or 'CON=OFF'
                    'DBP=ON' or 'DBP=OFF'
                    'SDC=ON' or 'SDC=OFF'
                    'SLD=ON' or 'SLD=OFF'
                    'TEN=ON' or 'TEN=OFF'

       ARRAY       Real array, input -- Sets an internal parameter.

       LENA        Integer, input -- The length of array ARRAY.

                   If an option is turned 'ON', then the remaining CONOP3 arguments can be used
                   to override the default settings of that option.

                   If the option is 'OFF', then the remaining arguments of the CONOP3 call can be
                   any dummy values.  Option settings will be returned to their default values.

                   The following options are defined by this subroutine:

       CHL     This parameter determines how the high and low contour values are set.  These
               contour values may be set by the program or by the user.  If CHL=OFF, the program
               examines the user's input data and determines both the high and low values.  If
               CHL=ON, the user must specify the desired high (HI) and low (FLO) values.  The
               default is CHL=OFF.

               If program set: CALL CONOP3('CHL=OFF',0.,0)

               If user set: CALL CONOP3('CHL=ON',ARRAY,2) where ARRAY(1)=HI, ARRAY(2)=FLO

               Note: The values supplied for contour increment and contour high and low values
               assume unscaled data values.  See the SDC parameter, below.

       CIL     This parameter determines how the contour increment (CINC) is set.  The increment
               is either calculated by the program (CIL=OFF) using the range of high and low
               values from the user's input data, or set by the user (CIL=ON).  The default is
               CIL=OFF.

               If program set: CALL CONOP3('CIL=OFF',0.,0)

               If user set:  CALL CONOP3('CIL=ON',CINC,1)

               Note: By default, ('CIL=OFF') the program will examine the user's input data and
               determine the contour interval (CINC) at some appropriate range between the level
               of high and low values supplied, usually generating between 15 and 20 contour
               levels.

               Example:   CALL CONOP3('CIL=ON',10.,1)
               will generate contours at increments of 10. units in user coordinates.

       CON     This parameter determines how the contour levels are set.  If CON=ON, the user
               must specify an array of contour values and the number of contour levels.  A
               maximum of NCL=30 contour levels is permitted.  If CON=OFF, NCL and the contour
               values are computed.  The default is OFF.

               If program set: CALL CONOP3('CON=OFF',0.,0)

               If user set: CALL CONOP3('CON=ON',ARRAY,NCL)

               Note: The real array (ARRAY) must have the contour levels ordered from smallest to
               largest.

               Warning: It is illegal to use the CON option when either CIL or CHL are activated.
               If this is done, the option call that detected the error will not be executed.

       DBP     This parameter determines how the dash pattern break point (BP) is set.  (Does not
               apply to entry CONRAQ.)  If DBP=ON, BP must be set by the user.  If DBP=OFF, the
               program will set BP to 0.  This is the default.

               If program set: CALL CONOP3('DBP=OFF',0.,0)

               If user set:  CALL CONOP3('DBP=ON',BP,1)

               Note: BP is a floating point number where the break for GTR and LSS contour dash
               patterns are defined.  BP is assumed to be given relative to the untransformed
               contours.

               To see how various dash line patterns can be assigned to various contours see
               parameter DBP in "man conop4".

       SDC     The parameter to determine how to scale the input data from which the contours are
               generated.  (Does not apply to entry CONRAQ.)  If SDC=ON, the scaling factor is
               set to ARRAY(1).  If SDC=OFF, the default scale factor of 1. is used.

               If program set: CALL CONOP3('SDC=OFF',0.,0)

               If user set:  CALL CONOP3('SDC=ON',ARRAY,1)

               Note: The data plotted on contour lines and the data plotted for relative minimums
               and maximums will be scaled by ARRAY.

       SLD     Input a polygon to define the extent of area to be contoured.  (Does not apply to
               entry CONRAQ.)  When this option is activated, only those contours within the
               shield are drawn.  The shield is a polygon specified by the user which must be
               given in the same coordinate range as the the data.  It must define only one
               polygon.

               To input a shield:
                 CALL CONOP3('SLD=ON',ARRAY,LENA)

               Otherwise:
                 CALL CONOP3('SLD=OFF',0.,0)

               Note: ARRAY is a real array LENA elements long.  The first LENA/2 elements are X
               coordinates and the second LENA/2 elements are Y coordinates.  This polygon must
               be closed, that is the first and last points in ARRAY must be the same.

               Example:

                DIMENSION SHLD(10)
                DATA SHLD/ 7.,10.,10.,7.,7.,
               1            7.,7.,10.,10.,7./
                CALL CONOP3 ('SLD=ON',SHLD,10)

       TEN     The parameter to determine the tension factor applied when smoothing contour lines
               using splines under tension.  (Does not apply to entry CONRAQ.)  If user set, the
               allowed range is from greater than zero to 30.  The higher the tension the less
               smoothing occurs.  The default value (TEN=OFF) is 2.5.

               If program set: CALL CONOP3('TEN=OFF',0.,0)

               If user set:  CALL CONOP3('TEN=ON',TENS,1)

               Note: This option is not available in the standard version of CONRAN.

USAGE

       CONOP3 is called to set parameters of type REAL before CONRAN, CONRAQ, or CONRAS are
       called to generate the contour plot.

EXAMPLES

       Use the command ncargex to see the following examples: tconaq, tconan, and tconas.

ACCESS

       To use CONOP3 load the NCAR Graphics libraries ncarg, ncarg_gks, and ncarg_c, preferably
       in that order.

MESSAGES

       See the conran_family man page for a description of all Conran_family error messages
       and/or informational messages.

SEE ALSO

       Online: conran_family, conran_family_params, conran, conraq, conras, conop1, conop2,
       conop4, conpack, conpack_params

       Hardcopy: NCAR Graphics Contouring and Mapping Tutorial; NCAR Graphics Fundamentals, UNIX
       Version; User's Guide for NCAR GKS-0A Graphics

COPYRIGHT

       Copyright (C) 1987-2009
       University Corporation for Atmospheric Research
       The use of this Software is governed by a License Agreement.