SUBROUTINE SGET10( 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 REAL RESULT * .. * .. Array Arguments .. REAL A( LDA, * ), B( LDB, * ), WORK( * ) * .. * * Purpose * ======= * * SGET10 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) REAL 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) REAL 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) REAL array, dimension (M) * * RESULT (output) REAL * RESULT = norm( A - B ) / ( norm(A) * M * EPS ) * * ===================================================================== * * .. Parameters .. REAL ONE, ZERO PARAMETER ( ONE = 1.0E+0, ZERO = 0.0E+0 ) * .. * .. Local Scalars .. INTEGER J REAL ANORM, EPS, UNFL, WNORM * .. * .. External Functions .. REAL SASUM, SLAMCH, SLANGE EXTERNAL SASUM, SLAMCH, SLANGE * .. * .. External Subroutines .. EXTERNAL SAXPY, SCOPY * .. * .. Intrinsic Functions .. INTRINSIC MAX, MIN, REAL * .. * .. Executable Statements .. * * Quick return if possible * IF( M.LE.0 .OR. N.LE.0 ) THEN RESULT = ZERO RETURN END IF * UNFL = SLAMCH( 'Safe minimum' ) EPS = SLAMCH( 'Precision' ) * WNORM = ZERO DO 10 J = 1, N CALL SCOPY( M, A( 1, J ), 1, WORK, 1 ) CALL SAXPY( M, -ONE, B( 1, J ), 1, WORK, 1 ) WNORM = MAX( WNORM, SASUM( N, WORK, 1 ) ) 10 CONTINUE * ANORM = MAX( SLANGE( '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, REAL( M ) ) / ( M*EPS ) END IF END IF * RETURN * * End of SGET10 * END