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[top]DLA_GBAMV(1LAPACK routine (version 3.2)DLA_GBAMV(1)NAMEDLA_GBAMV - performs one of the matrix-vector operations y := alpha*abs(A)*abs(x) + beta*abs(y),SYNOPSISSUBROUTINE DLA_GBAMV( TRANS, M, N, KL, KU, ALPHA, AB, LDAB, X, INCX, BETA, Y, INCY ) IMPLICIT NONE DOUBLE PRECISION ALPHA, BETA INTEGER INCX, INCY, LDAB, M, N, KL, KU, TRANS DOUBLE PRECISION AB( LDAB, * ), X( * ), Y( * )PURPOSEDLA_GEAMV performs one of the matrix-vector operations or y := alpha*abs(A)'*abs(x) + beta*abs(y), where alpha and beta are scalars, x and y are vectors and A is an m by n matrix. This function is primarily used in calculating error bounds. To pro‐ tect against underflow during evaluation, components in the resulting vector are perturbed away from zero by (N+1) times the underflow threshold. To prevent unnecessarily large errors for block-structure embedded in general matrices, "symbolically" zero components are not perturbed. A zero entry is con‐ sidered "symbolic" if all multiplications involved in computing that entry have at least one zero multiplicand.ARGUMENTSTRANS - INTEGER On entry, TRANS specifies the operation to be performed as fol‐ lows: BLAS_NO_TRANS y := alpha*abs(A)*abs(x) + beta*abs(y) BLAS_TRANS y := alpha*abs(A')*abs(x) + beta*abs(y) BLAS_CONJ_TRANS y := alpha*abs(A')*abs(x) + beta*abs(y) Unchanged on exit. M - INTEGER On entry, M specifies the number of rows of the matrix A. M must be at least zero. Unchanged on exit. N - INTEGER On entry, N specifies the number of columns of the matrix A. N must be at least zero. Unchanged on exit. KL - INTEGER The number of subdiagonals within the band of A. KL >= 0. KU - INTEGER The number of superdiagonals within the band of A. KU >= 0. ALPHA - DOUBLE PRECISION On entry, ALPHA specifies the scalar alpha. Unchanged on exit. A - DOUBLE PRECISION array of DIMENSION ( LDA, n ) Before entry, the leading m by n part of the array A must con‐ tain the matrix of coefficients. Unchanged on exit. LDA - INTEGER On entry, LDA specifies the first dimension of A as declared in the calling (sub) program. LDA must be at least max( 1, m ). Unchanged on exit. X - DOUBLE PRECISION array of DIMENSION at least ( 1 + ( n - 1 )*abs( INCX ) ) when TRANS = 'N' or 'n' and at least ( 1 + ( m - 1 )*abs( INCX ) ) otherwise. Before entry, the incremented array X must contain the vector x. Unchanged on exit. INCX - INTEGER On entry, INCX specifies the increment for the elements of X. INCX must not be zero. Unchanged on exit. BETA - DOUBLE PRECISION On entry, BETA specifies the scalar beta. When BETA is supplied as zero then Y need not be set on input. Unchanged on exit. Y - DOUBLE PRECISION array of DIMENSION at least ( 1 + ( m - 1 )*abs( INCY ) ) when TRANS = 'N' or 'n' and at least ( 1 + ( n - 1 )*abs( INCY ) ) otherwise. Before entry with BETA non-zero, the incremented array Y must contain the vector y. On exit, Y is overwritten by the updated vector y. INCY - INTEGER On entry, INCY specifies the increment for the elements of Y. INCY must not be zero. Unchanged on exit. Level 2 Blas rou‐ tine. LAPACK routine (version 3.2) November 2008 DLA_GBAMV(1)

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