SUBROUTINE DGET10( M, N, A, LDA, B, LDB, WORK, RESULT ) * * -- LAPACK test routine (version 3.1) -- * Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. * November 2006 * * .. Scalar Arguments .. INTEGER LDA, LDB, M, N DOUBLE PRECISION RESULT * .. * .. Array Arguments .. DOUBLE PRECISION A( LDA, * ), B( LDB, * ), WORK( * ) * .. * * Purpose * ======= * * DGET10 compares two matrices A and B and computes the ratio * RESULT = norm( A - B ) / ( norm(A) * M * EPS ) * * Arguments * ========= * * M (input) INTEGER * The number of rows of the matrices A and B. * * N (input) INTEGER * The number of columns of the matrices A and B. * * A (input) DOUBLE PRECISION array, dimension (LDA,N) * The m by n matrix A. * * LDA (input) INTEGER * The leading dimension of the array A. LDA >= max(1,M). * * B (input) DOUBLE PRECISION array, dimension (LDB,N) * The m by n matrix B. * * LDB (input) INTEGER * The leading dimension of the array B. LDB >= max(1,M). * * WORK (workspace) DOUBLE PRECISION array, dimension (M) * * RESULT (output) DOUBLE PRECISION * RESULT = norm( A - B ) / ( norm(A) * M * EPS ) * * ===================================================================== * * .. Parameters .. DOUBLE PRECISION ONE, ZERO PARAMETER ( ONE = 1.0D+0, ZERO = 0.0D+0 ) * .. * .. Local Scalars .. INTEGER J DOUBLE PRECISION ANORM, EPS, UNFL, WNORM * .. * .. External Functions .. DOUBLE PRECISION DASUM, DLAMCH, DLANGE EXTERNAL DASUM, DLAMCH, DLANGE * .. * .. External Subroutines .. EXTERNAL DAXPY, DCOPY * .. * .. Intrinsic Functions .. INTRINSIC DBLE, MAX, MIN * .. * .. Executable Statements .. * * Quick return if possible * IF( M.LE.0 .OR. N.LE.0 ) THEN RESULT = ZERO RETURN END IF * UNFL = DLAMCH( 'Safe minimum' ) EPS = DLAMCH( 'Precision' ) * WNORM = ZERO DO 10 J = 1, N CALL DCOPY( M, A( 1, J ), 1, WORK, 1 ) CALL DAXPY( M, -ONE, B( 1, J ), 1, WORK, 1 ) WNORM = MAX( WNORM, DASUM( N, WORK, 1 ) ) 10 CONTINUE * ANORM = MAX( DLANGE( '1', M, N, A, LDA, WORK ), UNFL ) * IF( ANORM.GT.WNORM ) THEN RESULT = ( WNORM / ANORM ) / ( M*EPS ) ELSE IF( ANORM.LT.ONE ) THEN RESULT = ( MIN( WNORM, M*ANORM ) / ANORM ) / ( M*EPS ) ELSE RESULT = MIN( WNORM / ANORM, DBLE( M ) ) / ( M*EPS ) END IF END IF * RETURN * * End of DGET10 * END