Technical Reference: Base Operating System and Extensions , Volume 2

SASUM, DASUM, SCASUM, or DZASUM Function

Returns the sum of absolute values of vector components.

BLAS Library (libblas.a)

REAL FUNCTION SASUM(N,X,INCX) INTEGER INCX, N REAL X(*)

DOUBLE PRECISION FUNCTION DASUM(N,X,INCX)
INTEGER INCX,N
DOUBLE PRECISION X(*)

REAL FUNCTION SCASUM(N,X,INCX)
INTEGER INCX,N
COMPLEX X(*)

DOUBLE PRECISION FUNCTION DZASUM(N,X,INCX)
INTEGER INCX,N
COMPLEX*16 X(*)

The SASUM, DASUM, SCASUM, or DZASUM function returns the sum of absolute values of vector components.

N	On entry, N specifies the number of elements in X and Y; unchanged on exit.
X	Vector of dimension at least (1 + (N-1) * abs(INCX) ); unchanged on exit.
INCX	On entry, INCX specifies the increment for the elements of X; INCX must be greater than 0; unchanged on exit.

For values of N <= 0, a value of 0 is returned.