Procedure

   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 value in array, 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 zero to ndim-1.

Detailed_Output

 
   The function returns the index of the input value in the input array. 
   Indices range from zero 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 memory cannot be allocated to create a Fortran-style version of
      the input order vector, the error SPICE(MALLOCFAILED) is signaled.
      The function returns -1 in this case.

   2) If ndim < 1 the value of the function is -1. This is not an error.

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

 
   The input order vector is assumed give the order of the elements of the
   input 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)
   W.L. Taber      (JPL)
   I.M. Underwood  (JPL) 
 

Version

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

Index_Entries

 
   binary search for an integer value 
 

Link to routine bschoi_c source file bschoi_c.c