Sum of the Absolute Values of a Vector

which is the l₁-norm of a vector x.

DZASUM and SCASUM compute

Note that DZASUM and SCASUM do not compute

which is the l₁-norm of a complex vector.

Calling Sequence

DL1 = DASUM (N, DX, INCX)

SL1 = SASUM (N, SX, INCX)

DL1 = DZASUM (N, ZX, INCX)

SL1 = SCASUM (N, CX, INCX)

double dasum (int n, double *dx, int incx)

real sasum (int n, float *sx, int incx)

double dzasum (int n, doublecomplex *zx, int incx)

real scasum (int n, complex *cx, int incx)

Arguments

N	Number of elements in the vector. N 0.
xX	Input vector X; the size of array X must be at least max(1,N*|INCX|).
INCX	Specifies the storage spacing between successive elements of the vector X. A value of one indicates that the elements of the vector are consecutive in memory. INCX > 0.
	If X refers to a two-dimensional array and the value of INCX is equal to the leading dimension of X then the elements of the vector will be a row of X.
	If X refers to a two-dimensional array and the value of INCX is equal to the leading dimension of X plus one then the elements of the vector will be a diagonal of X.

Sample Program

PROGRAM TEST

IMPLICIT NONE

C

INTEGER N

PARAMETER (N = 4)

C

DOUBLE PRECISION SUM, X(N)

INTEGER I, INCX

C

DOUBLE PRECISION DASUM

EXTERNAL DASUM

C

C Initialize the array X to store the vector x shown below.

C

C 1.0

C x = 2.0

C 3.0

C 4.0

C

DATA X / 1.0D0, 2.0D0, 3.0D0, 4.0D0 /

C

PRINT 1000

PRINT 1010, (X(I), I = 1, N)

INCX = 1

SUM = DASUM (N, X, INCX)

PRINT 1020, SUM

C

1000 FORMAT (1X, 'x:')

1010 FORMAT (3X, F3.1)

1020 FORMAT (/1X, 'The L-1 norm of x is ', F4.1)

C

END

Sample Output

x:
1.0
2.0
3.0
4.0
The L-1 norm of x is 10.0