Procedure

   SpiceInt lstlei_c ( SpiceInt            x,
                       SpiceInt            n,
                       ConstSpiceInt     * array ) 

Abstract

 
   Given a number x and an array of non-decreasing numbers, 
   find the index of the largest array element less than or equal 
   to x. 
 

Required_Reading

 
   None. 
 

Keywords

 
   SEARCH,  ARRAY 
 

Brief_I/O

 
   VARIABLE  I/O  DESCRIPTION 
   --------  ---  -------------------------------------------------- 
   x          I   Value to search against 
   n          I   Number elements in array
   array      I   Array of possible lower bounds 

   The function returns the index of the last element of array that
   is less than or equal to x. 
 

Detailed_Input

 
   x       Integer.

   n       Total number of elements in array. 

   array   Array of integers which forms a non-decreasing sequence.
           The elements of array need not be distinct.

 

Detailed_Output

 
   The function returns the index of the highest-indexed element in the 
   input array that is less than or equal to x.  The routine assumes
   the array elements are sorted in non-decreasing order.

   Indices range from 0 to n-1.
 
   If all elements of array are greater than x, this routine returns 
   the value -1.

Parameters

 
   None. 
 

Exceptions

 
   Error free.

   1) In the case that n is input with value less than or equal 
      to zero, the function returns -1.

   2) If the input array is not sorted in increasing order, the
      output of this routine are undefined.  No error is signaled.

Files

 
   None. 
  

Particulars

 
   Note:  If you need to find the first element of the array that 
          is greater than x, simply add 1 to the result returned 
          by this function and check to see if the result is 
          within the array bounds given by n. 
 

Examples

 
   1)  Let array be assigned the following values:

          array[0] = -2;
          array[1] = -2;
          array[2] =  0;
          array[3] =  1;
          array[4] =  1;
          array[5] = 11;


       The table below demonstrates the behavior of lstlei_c:

                    Call                       Returned Value
          =========================            ==============
          lstlei_c ( -3, 6, array )                -1

          lstlei_c ( -2, 6, array )                 1

          lstlei_c (  0, 6, array )                 2

          lstlei_c (  1, 6, array )                 4

          lstlei_c ( 12, 6, array )                 5

Restrictions

 
   If the sequence of elements in array is not non-decreasing, 
   the program will run to completion but the index found will 
   not mean anything. 
 

Literature_References

 
   None. 
 

Author_and_Institution

 
   N.J. Bachman    (JPL) 
   W.L. Taber      (JPL) 
 

Version

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

Index_Entries

 
   last integer element less_than_or_equal_to 
 

Link to routine lstlei_c source file lstlei_c.c