*  sample_fast_i.F
* 
*  This software was developed by the Thermal Modeling and Analysis
*  Project(TMAP) of the National Oceanographic and Atmospheric
*  Administration's (NOAA) Pacific Marine Environmental Lab(PMEL),
*  hereafter referred to as NOAA/PMEL/TMAP.
*
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*  the use of this software or in any product that includes this
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*
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* Ansley Manke June 2013
* Sample variable using a set of indices.
*
*
*  In this subroutine we provide information about
*  the function.  The user configurable information 
*  consists of the following:
* 
*  descr              Text description of the function
* 
*  num_args           Required number of arguments
* 
*  axis_inheritance   Type of axis for the result
*                        ( CUSTOM, IMPLIED_BY_ARGS, NORMAL, ABSTRACT )
*                        CUSTOM          - user defined axis
*                        IMPLIED_BY_ARGS - same axis as the incoming argument
*                        NORMAL          - the result is normal to this axis
*                        ABSTRACT        - an axis which only has index values
* 
*  piecemeal_ok       For memory optimization:
*                        axes where calculation may be performed piecemeal
*                        ( YES, NO )
* 
*
* For each argument we provide the following information:
*
* name               Text name for an argument
*
* unit               Text units for an argument
*
* desc               Text description of an argument
*
* axis_influence     Are this argument's axes the same as the result grid?
*                       ( YES, NO )
*
* axis_extend       How much does Ferret need to extend arg limits relative to result 
*


      SUBROUTINE sample_fast_i_init(id)

      IMPLICIT NONE
      INCLUDE 'ferret_cmn/EF_Util.cmn'

      INTEGER id, arg

* **********************************************************************
*                                            USER CONFIGURABLE PORTION |
*                                                                      |
*                                                                      V

      CALL ef_set_desc(id, 'Fast 1D sample variable using set of indices' )

      CALL ef_set_num_args(id, 2)
      CALL ef_set_has_vari_args(id, NO)
      CALL ef_set_axis_inheritance_6d(id, IMPLIED_BY_ARGS, NORMAL, 
     .                             NORMAL, NORMAL, NORMAL, NORMAL)
      CALL ef_set_piecemeal_ok_6d(id, NO, NO, NO, NO, NO, NO)

      arg = 1
      CALL ef_set_arg_name(id, arg, 'V')
      CALL ef_set_arg_desc(id, arg, 'Variable to sample')
      CALL ef_set_axis_influence_6d(id, arg, NO, NO, NO, NO, NO, NO)

      arg = 2
      CALL ef_set_arg_name(id, arg, 'Indices')
      CALL ef_set_arg_desc(id, arg, 'List of indices at which to sample ')
      CALL ef_set_axis_influence_6d(id, arg, YES, NO, NO, NO, NO, NO)

*                                                                      ^
*                                                                      |
*                                            USER CONFIGURABLE PORTION |
* **********************************************************************

      RETURN 
      END

*  In this subroutine we compute the result
* 
      SUBROUTINE sample_fast_i_compute(id, arg_1, arg_2, result)

      IMPLICIT NONE
      INCLUDE 'ferret_cmn/EF_Util.cmn'
      INCLUDE 'ferret_cmn/EF_mem_subsc.cmn'

      INTEGER id

* Function is intended only for variables in the x direction

      REAL arg_1(mem1lox:mem1hix)
      REAL arg_2(mem2lox:mem2hix)
      REAL result(memreslox:memreshix)

* After initialization, the 'res_' arrays contain indexing information 
* for the result axes.  The 'arg_' arrays will contain the indexing 
* information for each variable's axes. 

      INTEGER res_lo_ss(6),
     .        res_hi_ss(6),
     .        res_incr (6)
      INTEGER arg_lo_ss(6,EF_MAX_ARGS),
     .        arg_hi_ss(6,EF_MAX_ARGS),
     .        arg_incr (6,EF_MAX_ARGS)

      REAL bad_flag(EF_MAX_ARGS), bad_flag_result


* **********************************************************************
*                                            USER CONFIGURABLE PORTION |
*                                                                      |
*                                                                      V

      INTEGER	i, i2, isample

      CALL ef_get_res_subscripts_6d(id, res_lo_ss, res_hi_ss, res_incr)
      CALL ef_get_arg_subscripts_6d(id, arg_lo_ss, arg_hi_ss, arg_incr)
      CALL ef_get_bad_flags(id, bad_flag, bad_flag_result)

      i2 = arg_lo_ss(X_AXIS,ARG2)
      DO 100 i = res_lo_ss(X_AXIS), res_hi_ss(X_AXIS)
      
         result(i) = bad_flag_result
         IF (arg_2(i2) .NE. bad_flag(ARG2)) THEN
            isample = INT(arg_2(i2))
            result(i) = arg_1(isample)
	 ENDIF
	 i2 = i2 + arg_incr(X_AXIS,ARG2)
  100 CONTINUE

      RETURN

      RETURN
      END
