asum(3F)

NAME
     SASUM, DASUM, SCASUM, DZASUM - Sums the absolute value of elements in
     a real or complex vector

SYNOPSIS
     Real

        sum = SASUM (n, x, incx)

     Double precision

        sum = DASUM (n, x, incx)

     Complex

        sum = SCASUM (n, x, incx)

     Double complex

        sum = DZASUM (n, x, incx)

DESCRIPTION
     SASUM and DASUM sum the absolute values of the elements of a real
     vector, as follows:

                                n
               sum <- ||x||1 = Sum |xi|
                               i=1

     where x is a real vector of length n.

     SCASUM and DZASUM sum the absolute values of the real and imaginary
     parts of the elements of a complex vector, as follows:



               sum <- ||Real(x)||1 + Imag(x)||1=

                       n                n
                      Sum |Real(xi)| + Sum |Imag(xj)|
                      i=1              j=1

     where x is a complex vector of length n.

     These functions have the following arguments:

     sum       Sum of values.
               SASUM: Real sum of the absolute values of the elements of x.
               DASUM: Double precision sum of the absolute values of the
               elements of x.
               SCASUM: Real sum of the absolute values of the real and
               imaginary parts of the elements of x.
               DZASUM: Double precision sum of the absolute values of the
               real and imaginary parts of the elements of x.

     n         Integer.  (input)
               Number of elements in the vector to be summed.  If n <= 0,
               these routines return 0.

     x         Array of dimension (n-1) * |incx| + 1. (input)
               SASUM: Real array.
               DASUM: Double precision array.
               SCASUM: Complex array.
               DZASUM:  Double complex array.

               Array x contains the vector to be summed.

     incx      Integer.  (input)
               Increment between elements of x.  If incx = 0, the results
               will be unpredictable.

NOTES
     These routines are 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)