LAPACK  3.8.0
LAPACK: Linear Algebra PACKage

◆ dzsum1()

double precision function dzsum1 ( integer  N,
complex*16, dimension( * )  CX,
integer  INCX 
)

DZSUM1 forms the 1-norm of the complex vector using the true absolute value.

Download DZSUM1 + dependencies [TGZ] [ZIP] [TXT]

Purpose:
 DZSUM1 takes the sum of the absolute values of a complex
 vector and returns a double precision result.

 Based on DZASUM from the Level 1 BLAS.
 The change is to use the 'genuine' absolute value.
Parameters
[in]N
          N is INTEGER
          The number of elements in the vector CX.
[in]CX
          CX is COMPLEX*16 array, dimension (N)
          The vector whose elements will be summed.
[in]INCX
          INCX is INTEGER
          The spacing between successive values of CX.  INCX > 0.
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date
December 2016
Contributors:
Nick Higham for use with ZLACON.

Definition at line 83 of file dzsum1.f.

83 *
84 * -- LAPACK auxiliary routine (version 3.7.0) --
85 * -- LAPACK is a software package provided by Univ. of Tennessee, --
86 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
87 * December 2016
88 *
89 * .. Scalar Arguments ..
90  INTEGER incx, n
91 * ..
92 * .. Array Arguments ..
93  COMPLEX*16 cx( * )
94 * ..
95 *
96 * =====================================================================
97 *
98 * .. Local Scalars ..
99  INTEGER i, nincx
100  DOUBLE PRECISION stemp
101 * ..
102 * .. Intrinsic Functions ..
103  INTRINSIC abs
104 * ..
105 * .. Executable Statements ..
106 *
107  dzsum1 = 0.0d0
108  stemp = 0.0d0
109  IF( n.LE.0 )
110  $ RETURN
111  IF( incx.EQ.1 )
112  $ GO TO 20
113 *
114 * CODE FOR INCREMENT NOT EQUAL TO 1
115 *
116  nincx = n*incx
117  DO 10 i = 1, nincx, incx
118 *
119 * NEXT LINE MODIFIED.
120 *
121  stemp = stemp + abs( cx( i ) )
122  10 CONTINUE
123  dzsum1 = stemp
124  RETURN
125 *
126 * CODE FOR INCREMENT EQUAL TO 1
127 *
128  20 CONTINUE
129  DO 30 i = 1, n
130 *
131 * NEXT LINE MODIFIED.
132 *
133  stemp = stemp + abs( cx( i ) )
134  30 CONTINUE
135  dzsum1 = stemp
136  RETURN
137 *
138 * End of DZSUM1
139 *
double precision function dzsum1(N, CX, INCX)
DZSUM1 forms the 1-norm of the complex vector using the true absolute value.
Definition: dzsum1.f:83