lapack-sys 0.15.0

The package provides bindings to LAPACK (Fortran).
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129

*> \brief \b SNRM2
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*  Definition:
*  ===========
*
*       REAL FUNCTION SNRM2(N,X,INCX)
*
*       .. Scalar Arguments ..
*       INTEGER INCX,N
*       ..
*       .. Array Arguments ..
*       REAL X(*)
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> SNRM2 returns the euclidean norm of a vector via the function
*> name, so that
*>
*>    SNRM2 := sqrt( x'*x ).
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>         number of elements in input vector(s)
*> \endverbatim
*>
*> \param[in] X
*> \verbatim
*>          X is REAL array, dimension ( 1 + ( N - 1 )*abs( INCX ) )
*> \endverbatim
*>
*> \param[in] INCX
*> \verbatim
*>          INCX is INTEGER
*>         storage spacing between elements of SX
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \ingroup single_blas_level1
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  -- This version written on 25-October-1982.
*>     Modified on 14-October-1993 to inline the call to SLASSQ.
*>     Sven Hammarling, Nag Ltd.
*> \endverbatim
*>
*  =====================================================================
      REAL FUNCTION SNRM2(N,X,INCX)
*
*  -- Reference BLAS level1 routine --
*  -- Reference BLAS is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*
*     .. Scalar Arguments ..
      INTEGER INCX,N
*     ..
*     .. Array Arguments ..
      REAL X(*)
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      REAL ONE,ZERO
      PARAMETER (ONE=1.0E+0,ZERO=0.0E+0)
*     ..
*     .. Local Scalars ..
      REAL ABSXI,NORM,SCALE,SSQ
      INTEGER IX
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC ABS,SQRT
*     ..
      IF (N.LT.1 .OR. INCX.LT.1) THEN
          NORM = ZERO
      ELSE IF (N.EQ.1) THEN
          NORM = ABS(X(1))
      ELSE
          SCALE = ZERO
          SSQ = ONE
*        The following loop is equivalent to this call to the LAPACK
*        auxiliary routine:
*        CALL SLASSQ( N, X, INCX, SCALE, SSQ )
*
          DO 10 IX = 1,1 + (N-1)*INCX,INCX
              IF (X(IX).NE.ZERO) THEN
                  ABSXI = ABS(X(IX))
                  IF (SCALE.LT.ABSXI) THEN
                      SSQ = ONE + SSQ* (SCALE/ABSXI)**2
                      SCALE = ABSXI
                  ELSE
                      SSQ = SSQ + (ABSXI/SCALE)**2
                  END IF
              END IF
   10     CONTINUE
          NORM = SCALE*SQRT(SSQ)
      END IF
*
      SNRM2 = NORM
      RETURN
*
*     End of SNRM2.
*
      END