LAPACK  3.10.0
LAPACK: Linear Algebra PACKage

◆ sasum()

real function sasum ( integer  N,
real, dimension(*)  SX,
integer  INCX 
)

SASUM

Purpose:
    SASUM takes the sum of the absolute values.
    uses unrolled loops for increment equal to one.
Parameters
[in]N
          N is INTEGER
         number of elements in input vector(s)
[in]SX
          SX is REAL array, dimension ( 1 + ( N - 1 )*abs( INCX ) )
[in]INCX
          INCX is INTEGER
         storage spacing between elements of SX
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Further Details:
     jack dongarra, linpack, 3/11/78.
     modified 3/93 to return if incx .le. 0.
     modified 12/3/93, array(1) declarations changed to array(*)

Definition at line 71 of file sasum.f.

72 *
73 * -- Reference BLAS level1 routine --
74 * -- Reference BLAS is a software package provided by Univ. of Tennessee, --
75 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
76 *
77 * .. Scalar Arguments ..
78  INTEGER INCX,N
79 * ..
80 * .. Array Arguments ..
81  REAL SX(*)
82 * ..
83 *
84 * =====================================================================
85 *
86 * .. Local Scalars ..
87  REAL STEMP
88  INTEGER I,M,MP1,NINCX
89 * ..
90 * .. Intrinsic Functions ..
91  INTRINSIC abs,mod
92 * ..
93  sasum = 0.0e0
94  stemp = 0.0e0
95  IF (n.LE.0 .OR. incx.LE.0) RETURN
96  IF (incx.EQ.1) THEN
97 * code for increment equal to 1
98 *
99 *
100 * clean-up loop
101 *
102  m = mod(n,6)
103  IF (m.NE.0) THEN
104  DO i = 1,m
105  stemp = stemp + abs(sx(i))
106  END DO
107  IF (n.LT.6) THEN
108  sasum = stemp
109  RETURN
110  END IF
111  END IF
112  mp1 = m + 1
113  DO i = mp1,n,6
114  stemp = stemp + abs(sx(i)) + abs(sx(i+1)) +
115  $ abs(sx(i+2)) + abs(sx(i+3)) +
116  $ abs(sx(i+4)) + abs(sx(i+5))
117  END DO
118  ELSE
119 *
120 * code for increment not equal to 1
121 *
122  nincx = n*incx
123  DO i = 1,nincx,incx
124  stemp = stemp + abs(sx(i))
125  END DO
126  END IF
127  sasum = stemp
128  RETURN
129 *
130 * End of SASUM
131 *
real function sasum(N, SX, INCX)
SASUM
Definition: sasum.f:72
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