Procedure

   bschoi_c ( Binary search with order vector, integer ) 

   SpiceInt bschoi_c ( SpiceInt          value,
                       SpiceInt          ndim,
                       ConstSpiceInt   * array,
                       ConstSpiceInt   * order  )

Abstract

   Do a binary search for a given value within an integer array,
   accompanied by an order vector. Return the index of the
   matching array entry, or -1 if the key value is not found.

Required_Reading

   None.

Keywords

   ARRAY
   SEARCH

Brief_I/O

   VARIABLE  I/O  DESCRIPTION
   --------  ---  --------------------------------------------------
   value      I   Value to find in `array'.
   ndim       I   Dimension of `array'.
   array      I   Array to be searched.
   order      I   Order vector.

   The function returns the index of the first matching array element
   or -1 if the value is not found.

Detailed_Input

   value       is the value to be found in the input array.

   ndim        is the number of elements in the input array.

   array       is the array to be searched.

   order       is an order vector which can be used to access the
               elements of `array' in order. The contents of order are a
               permutation of the sequence of integers ranging from 0 to
               ndim-1.

Detailed_Output

   The function returns the index of the specified value in the input
   array. Indices range from 0 to ndim-1.

   If the input array does not contain the specified value, the
   function returns -1.

   If the input array contains more than one occurrence of the
   specified value, the returned index may point to any of the
   occurrences.

Parameters

   None.

Exceptions

   1)  If ndim < 1, the value of the function is -1.

   2)  If memory cannot be allocated to create the temporary variable
       required for the execution of the underlying Fortran routine,
       the error SPICE(MALLOCFAILED) is signaled. The function
       returns the value -1.

Files

   None.

Particulars

   A binary search is performed on the input array, whose order is
   given by an associated order vector. If an element of the array is
   found to match the input value, the index of that element is
   returned. If no matching element is found, -1 is returned.

Examples

   Let `array' and `order' contain the following elements:

      array         order
      -----------   -----
        100             1
          1             2
         10             0
      10000             4
       1000             3

   Then

      bschoi_c (  1000, 5, array, order )  ==   4
      bschoi_c (     1, 5, array, order )  ==   1
      bschoi_c ( 10000, 5, array, order )  ==   3
      bschoi_c (    -1, 5, array, order )  ==  -1
      bschoi_c (    17, 5, array, order )  ==  -1

   That is,

      array[4] ==  1000
      array[1] ==     1
      array[3] == 10000

Restrictions

   1)  `order' is assumed to give the order of the elements of `array'
       in increasing order. If this condition is not met, the results
       of bschoi_c are unpredictable.

Literature_References

   None.

Author_and_Institution

   N.J. Bachman        (JPL)
   J. Diaz del Rio     (ODC Space)
   W.L. Taber          (JPL)
   I.M. Underwood      (JPL)

Version

   -CSPICE Version 1.0.1, 08-JUL-2021 (JDR)

       Edited the header to comply with NAIF standard. Updated
       -Index_Entries to better explain the objective of this function.

   -CSPICE Version 1.0.0, 10-JUL-2002 (NJB) (WLT) (IMU)

Index_Entries

   binary search for an integer using an order vector