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IMSL Name:  SRCH/DSRCH (Single/Double precision version)
 
Revised:    March 19, 1991
 
Purpose:    Search a sorted vector for a given scalar and return
            its index.
 
Usage:      CALL SRCH (N, VALUE, X, INCX, INDEX)
 
Arguments:
   N      - Length of vector Y.  (Input)
   VALUE  - Scalar to be searched for in Y.  (Input)
   X      - Vector of length N*INCX.  (Input)
            Y is obtained from X for I = 1, 2, ..., N by
            Y(I) = X(1+(I-1)*INCX).  Y(1), Y(2), ..., Y(N) must
            be in ascending order.
   INCX   - Displacement between elements of X.  (Input)
            INCX must be greater than zero.
   INDEX  - Index of Y pointing to VALUE.  (Output)
            If INDEX is positive, VALUE is found in Y.  If INDEX is
            negative, VALUE is not found in Y.
                INDEX     Location of VALUE
              1 thru N   VALUE = Y(INDEX)
                 -1      VALUE < Y(1) or N = 0
             -N thru -2  Y(-INDEX-1) < VALUE < Y(-INDEX)
               -(N+1)    VALUE > Y(N)
 
Keywords:   Utilities; Binary search; Logarithmic search; Bisection
 
GAMS:       N5b; N5c
 
Chapters:   MATH/LIBRARY Utilities
            STAT/LIBRARY Utilities
 
Page No.:   MATH/LIBRARY User's Manual page 1291
            STAT/LIBRARY User's Manual page 1412