SASUM/DASUM/IASUM/SCASUM/DZASUM

Sum of magnitudes

 

 

Indexing Conventions” in the introduction to this

 

 

chapter.

Output

s

If n ≤ 0, then s = 0. Otherwise, s is the sum of

 

 

magnitudes of the elements of x.

Fortran

REAL*4 FUNCTION SASUM (N, X,INCX)

Equivalent

REAL*4 X(*)

SASUM = 0.0

IF ( N .LE. 0 ) RETURN

IX = 1

INCXA = ABS ( INCX )

DO 10 I = 1, N

SASUM = SASUM + ABS ( X(IX) )

IX = IX + INCXA

10CONTINUE RETURN END

Example Compute the sum of magnitudes of the elements of a REAL*8 vector x, where x is a vector 10 elements long stored in a one-dimensional array X of dimension 20.

INTEGER*4

N,INCX

REAL*8

S,DASUM,X(20)

N =

10

 

INCX = 1

 

S =

DASUM

(N,X,INCX)

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