LAPACK 3.11.0
LAPACK: Linear Algebra PACKage
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dget10.f
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1*> \brief \b DGET10
2*
3* =========== DOCUMENTATION ===========
4*
5* Online html documentation available at
6* http://www.netlib.org/lapack/explore-html/
7*
8* Definition:
9* ===========
10*
11* SUBROUTINE DGET10( M, N, A, LDA, B, LDB, WORK, RESULT )
12*
13* .. Scalar Arguments ..
14* INTEGER LDA, LDB, M, N
15* DOUBLE PRECISION RESULT
16* ..
17* .. Array Arguments ..
18* DOUBLE PRECISION A( LDA, * ), B( LDB, * ), WORK( * )
19* ..
20*
21*
22*> \par Purpose:
23* =============
24*>
25*> \verbatim
26*>
27*> DGET10 compares two matrices A and B and computes the ratio
28*> RESULT = norm( A - B ) / ( norm(A) * M * EPS )
29*> \endverbatim
30*
31* Arguments:
32* ==========
33*
34*> \param[in] M
35*> \verbatim
36*> M is INTEGER
37*> The number of rows of the matrices A and B.
38*> \endverbatim
39*>
40*> \param[in] N
41*> \verbatim
42*> N is INTEGER
43*> The number of columns of the matrices A and B.
44*> \endverbatim
45*>
46*> \param[in] A
47*> \verbatim
48*> A is DOUBLE PRECISION array, dimension (LDA,N)
49*> The m by n matrix A.
50*> \endverbatim
51*>
52*> \param[in] LDA
53*> \verbatim
54*> LDA is INTEGER
55*> The leading dimension of the array A. LDA >= max(1,M).
56*> \endverbatim
57*>
58*> \param[in] B
59*> \verbatim
60*> B is DOUBLE PRECISION array, dimension (LDB,N)
61*> The m by n matrix B.
62*> \endverbatim
63*>
64*> \param[in] LDB
65*> \verbatim
66*> LDB is INTEGER
67*> The leading dimension of the array B. LDB >= max(1,M).
68*> \endverbatim
69*>
70*> \param[out] WORK
71*> \verbatim
72*> WORK is DOUBLE PRECISION array, dimension (M)
73*> \endverbatim
74*>
75*> \param[out] RESULT
76*> \verbatim
77*> RESULT is DOUBLE PRECISION
78*> RESULT = norm( A - B ) / ( norm(A) * M * EPS )
79*> \endverbatim
80*
81* Authors:
82* ========
83*
84*> \author Univ. of Tennessee
85*> \author Univ. of California Berkeley
86*> \author Univ. of Colorado Denver
87*> \author NAG Ltd.
88*
89*> \ingroup double_eig
90*
91* =====================================================================
92 SUBROUTINE dget10( M, N, A, LDA, B, LDB, WORK, RESULT )
93*
94* -- LAPACK test routine --
95* -- LAPACK is a software package provided by Univ. of Tennessee, --
96* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
97*
98* .. Scalar Arguments ..
99 INTEGER LDA, LDB, M, N
100 DOUBLE PRECISION RESULT
101* ..
102* .. Array Arguments ..
103 DOUBLE PRECISION A( LDA, * ), B( LDB, * ), WORK( * )
104* ..
105*
106* =====================================================================
107*
108* .. Parameters ..
109 DOUBLE PRECISION ONE, ZERO
110 parameter( one = 1.0d+0, zero = 0.0d+0 )
111* ..
112* .. Local Scalars ..
113 INTEGER J
114 DOUBLE PRECISION ANORM, EPS, UNFL, WNORM
115* ..
116* .. External Functions ..
117 DOUBLE PRECISION DASUM, DLAMCH, DLANGE
118 EXTERNAL dasum, dlamch, dlange
119* ..
120* .. External Subroutines ..
121 EXTERNAL daxpy, dcopy
122* ..
123* .. Intrinsic Functions ..
124 INTRINSIC dble, max, min
125* ..
126* .. Executable Statements ..
127*
128* Quick return if possible
129*
130 IF( m.LE.0 .OR. n.LE.0 ) THEN
131 result = zero
132 RETURN
133 END IF
134*
135 unfl = dlamch( 'Safe minimum' )
136 eps = dlamch( 'Precision' )
137*
138 wnorm = zero
139 DO 10 j = 1, n
140 CALL dcopy( m, a( 1, j ), 1, work, 1 )
141 CALL daxpy( m, -one, b( 1, j ), 1, work, 1 )
142 wnorm = max( wnorm, dasum( n, work, 1 ) )
143 10 CONTINUE
144*
145 anorm = max( dlange( '1', m, n, a, lda, work ), unfl )
146*
147 IF( anorm.GT.wnorm ) THEN
148 result = ( wnorm / anorm ) / ( m*eps )
149 ELSE
150 IF( anorm.LT.one ) THEN
151 result = ( min( wnorm, m*anorm ) / anorm ) / ( m*eps )
152 ELSE
153 result = min( wnorm / anorm, dble( m ) ) / ( m*eps )
154 END IF
155 END IF
156*
157 RETURN
158*
159* End of DGET10
160*
161 END
subroutine dcopy(N, DX, INCX, DY, INCY)
DCOPY
Definition: dcopy.f:82
subroutine daxpy(N, DA, DX, INCX, DY, INCY)
DAXPY
Definition: daxpy.f:89
subroutine dget10(M, N, A, LDA, B, LDB, WORK, RESULT)
DGET10
Definition: dget10.f:93