 LAPACK  3.6.1 LAPACK: Linear Algebra PACKage
 real function scnrm2 ( integer N, complex, dimension(*) X, integer INCX )

SCNRM2

Purpose:
``` SCNRM2 returns the euclidean norm of a vector via the function
name, so that

SCNRM2 := sqrt( x**H*x )```
Date
November 2011
Further Details:
```  -- This version written on 25-October-1982.
Modified on 14-October-1993 to inline the call to CLASSQ.
Sven Hammarling, Nag Ltd.```

Definition at line 56 of file scnrm2.f.

56 *
57 * -- Reference BLAS level1 routine (version 3.4.0) --
58 * -- Reference BLAS is a software package provided by Univ. of Tennessee, --
59 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
60 * November 2011
61 *
62 * .. Scalar Arguments ..
63  INTEGER incx,n
64 * ..
65 * .. Array Arguments ..
66  COMPLEX x(*)
67 * ..
68 *
69 * =====================================================================
70 *
71 * .. Parameters ..
72  REAL one,zero
73  parameter(one=1.0e+0,zero=0.0e+0)
74 * ..
75 * .. Local Scalars ..
76  REAL norm,scale,ssq,temp
77  INTEGER ix
78 * ..
79 * .. Intrinsic Functions ..
80  INTRINSIC abs,aimag,REAL,sqrt
81 * ..
82  IF (n.LT.1 .OR. incx.LT.1) THEN
83  norm = zero
84  ELSE
85  scale = zero
86  ssq = one
87 * The following loop is equivalent to this call to the LAPACK
88 * auxiliary routine:
89 * CALL CLASSQ( N, X, INCX, SCALE, SSQ )
90 *
91  DO 10 ix = 1,1 + (n-1)*incx,incx
92  IF (REAL(x(ix)).NE.zero) then
93  temp = abs(REAL(x(ix)))
94  IF (scale.LT.temp) THEN
95  ssq = one + ssq* (scale/temp)**2
96  scale = temp
97  ELSE
98  ssq = ssq + (temp/scale)**2
99  END IF
100  END IF
101  IF (aimag(x(ix)).NE.zero) THEN
102  temp = abs(aimag(x(ix)))
103  IF (scale.LT.temp) THEN
104  ssq = one + ssq* (scale/temp)**2
105  scale = temp
106  ELSE
107  ssq = ssq + (temp/scale)**2
108  END IF
109  END IF
110  10 CONTINUE
111  norm = scale*sqrt(ssq)
112  END IF
113 *
114  scnrm2 = norm
115  RETURN
116 *
117 * End of SCNRM2.
118 *
real function scnrm2(N, X, INCX)
SCNRM2
Definition: scnrm2.f:56

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