ISAMAX(3)       BLAS routine of NEC Numeric Library Collection       ISAMAX(3)



NAME
       ISAMAX - BLAS level one, maximum index function

SYNOPSIS
       INTEGER FUNCTION ISAMAX ( n, x, incx )

           INTEGER               n, incx

           REAL                  x


DESCRIPTION
       ISAMAX searches a real vector for the first occurrence of the the maxi-
       mum absolute value. The vector x has length n and increment incx.

       ISAMAX returns the first index i such that
               |x | = MAX |x | : j = 1, ..., n
                 i          j
       where x  is an element of a real vector.
              j

ARGUMENTS
       n       INTEGER. (input)
               Number of elements to process in the vector to be searched.  If
               n <= 0, these routines return 0.

       x       REAL. (input)
               Array of dimension (n-1) * |incx| + 1.
               Array x contains the vector to be searched.

       incx    INTEGER. (input)
               Increment between elements of x.

RETURN VALUES
       ISAMAX  INTEGER. (output)
               Return  the first index of the maximum absolute value of vector
               x.  The vector x has length n and increment incx.

NOTES
       This routine is Level 1  Basic  Linear  Algebra  Subprograms  (Level  1
       BLAS).

       When working backward (incx < 0), each routine starts at the end of the
       vector and moves backward, as follows:

            x(1-incx * (n-1)), x(1-incx * (n-2)), ..., x(1)

       The largest absolute value is:

            ABS (x(1+(index-1) * incx)) when incx > 0

            ABS (x(1+(n-index) * |incx|)) when incx < 0




BLAS routine                                                         ISAMAX(3)