 LAPACK 3.11.0 LAPACK: Linear Algebra PACKage
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## ◆ dget10()

 subroutine dget10 ( integer M, integer N, double precision, dimension( lda, * ) A, integer LDA, double precision, dimension( ldb, * ) B, integer LDB, double precision, dimension( * ) WORK, double precision RESULT )

DGET10

Purpose:
``` DGET10 compares two matrices A and B and computes the ratio
RESULT = norm( A - B ) / ( norm(A) * M * EPS )```
Parameters
 [in] M ``` M is INTEGER The number of rows of the matrices A and B.``` [in] N ``` N is INTEGER The number of columns of the matrices A and B.``` [in] A ``` A is DOUBLE PRECISION array, dimension (LDA,N) The m by n matrix A.``` [in] LDA ``` LDA is INTEGER The leading dimension of the array A. LDA >= max(1,M).``` [in] B ``` B is DOUBLE PRECISION array, dimension (LDB,N) The m by n matrix B.``` [in] LDB ``` LDB is INTEGER The leading dimension of the array B. LDB >= max(1,M).``` [out] WORK ` WORK is DOUBLE PRECISION array, dimension (M)` [out] RESULT ``` RESULT is DOUBLE PRECISION RESULT = norm( A - B ) / ( norm(A) * M * EPS )```

Definition at line 92 of file dget10.f.

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*
double precision function dlamch(CMACH)
DLAMCH
Definition: dlamch.f:69
subroutine dcopy(N, DX, INCX, DY, INCY)
DCOPY
Definition: dcopy.f:82
double precision function dasum(N, DX, INCX)
DASUM
Definition: dasum.f:71
subroutine daxpy(N, DA, DX, INCX, DY, INCY)
DAXPY
Definition: daxpy.f:89
double precision function dlange(NORM, M, N, A, LDA, WORK)
DLANGE returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value ...
Definition: dlange.f:114
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