.TH "SRC/zla_gbamv.f" 3 "Version 3.12.0" "LAPACK" \" -*- nroff -*-
.ad l
.nh
.SH NAME
SRC/zla_gbamv.f
.SH SYNOPSIS
.br
.PP
.SS "Functions/Subroutines"

.in +1c
.ti -1c
.RI "subroutine \fBzla_gbamv\fP (trans, m, n, kl, ku, alpha, ab, ldab, x, incx, beta, y, incy)"
.br
.RI "\fBZLA_GBAMV\fP performs a matrix-vector operation to calculate error bounds\&. "
.in -1c
.SH "Function/Subroutine Documentation"
.PP 
.SS "subroutine zla_gbamv (integer trans, integer m, integer n, integer kl, integer ku, double precision alpha, complex*16, dimension( ldab, * ) ab, integer ldab, complex*16, dimension( * ) x, integer incx, double precision beta, double precision, dimension( * ) y, integer incy)"

.PP
\fBZLA_GBAMV\fP performs a matrix-vector operation to calculate error bounds\&.  
.PP
\fBPurpose:\fP
.RS 4

.PP
.nf
!>
!> ZLA_GBAMV  performs one of the matrix-vector operations
!>
!>         y := alpha*abs(A)*abs(x) + beta*abs(y),
!>    or   y := alpha*abs(A)**T*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 protect 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,
!>  zero components are not perturbed\&.  A zero
!> entry is considered  if all multiplications involved
!> in computing that entry have at least one zero multiplicand\&.
!> 
.fi
.PP
 
.RE
.PP
\fBParameters\fP
.RS 4
\fITRANS\fP 
.PP
.nf
!>          TRANS is INTEGER
!>           On entry, TRANS specifies the operation to be performed as
!>           follows:
!>
!>             BLAS_NO_TRANS      y := alpha*abs(A)*abs(x) + beta*abs(y)
!>             BLAS_TRANS         y := alpha*abs(A**T)*abs(x) + beta*abs(y)
!>             BLAS_CONJ_TRANS    y := alpha*abs(A**T)*abs(x) + beta*abs(y)
!>
!>           Unchanged on exit\&.
!> 
.fi
.PP
.br
\fIM\fP 
.PP
.nf
!>          M is INTEGER
!>           On entry, M specifies the number of rows of the matrix A\&.
!>           M must be at least zero\&.
!>           Unchanged on exit\&.
!> 
.fi
.PP
.br
\fIN\fP 
.PP
.nf
!>          N is INTEGER
!>           On entry, N specifies the number of columns of the matrix A\&.
!>           N must be at least zero\&.
!>           Unchanged on exit\&.
!> 
.fi
.PP
.br
\fIKL\fP 
.PP
.nf
!>          KL is INTEGER
!>           The number of subdiagonals within the band of A\&.  KL >= 0\&.
!> 
.fi
.PP
.br
\fIKU\fP 
.PP
.nf
!>          KU is INTEGER
!>           The number of superdiagonals within the band of A\&.  KU >= 0\&.
!> 
.fi
.PP
.br
\fIALPHA\fP 
.PP
.nf
!>          ALPHA is DOUBLE PRECISION
!>           On entry, ALPHA specifies the scalar alpha\&.
!>           Unchanged on exit\&.
!> 
.fi
.PP
.br
\fIAB\fP 
.PP
.nf
!>          AB is COMPLEX*16 array, dimension ( LDAB, n )
!>           Before entry, the leading m by n part of the array AB must
!>           contain the matrix of coefficients\&.
!>           Unchanged on exit\&.
!> 
.fi
.PP
.br
\fILDAB\fP 
.PP
.nf
!>          LDAB is INTEGER
!>           On entry, LDAB specifies the first dimension of AB as declared
!>           in the calling (sub) program\&. LDAB must be at least
!>           max( 1, m )\&.
!>           Unchanged on exit\&.
!> 
.fi
.PP
.br
\fIX\fP 
.PP
.nf
!>          X is COMPLEX*16 array, dimension
!>           ( 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\&.
!> 
.fi
.PP
.br
\fIINCX\fP 
.PP
.nf
!>          INCX is INTEGER
!>           On entry, INCX specifies the increment for the elements of
!>           X\&. INCX must not be zero\&.
!>           Unchanged on exit\&.
!> 
.fi
.PP
.br
\fIBETA\fP 
.PP
.nf
!>          BETA is 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\&.
!> 
.fi
.PP
.br
\fIY\fP 
.PP
.nf
!>          Y is DOUBLE PRECISION array, dimension
!>           ( 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\&.
!>           If either m or n is zero, then Y not referenced and the function
!>           performs a quick return\&.
!> 
.fi
.PP
.br
\fIINCY\fP 
.PP
.nf
!>          INCY is INTEGER
!>           On entry, INCY specifies the increment for the elements of
!>           Y\&. INCY must not be zero\&.
!>           Unchanged on exit\&.
!>
!>  Level 2 Blas routine\&.
!> 
.fi
.PP
 
.RE
.PP
\fBAuthor\fP
.RS 4
Univ\&. of Tennessee 

.PP
Univ\&. of California Berkeley 

.PP
Univ\&. of Colorado Denver 

.PP
NAG Ltd\&. 
.RE
.PP

.PP
Definition at line \fB186\fP of file \fBzla_gbamv\&.f\fP\&.
.SH "Author"
.PP 
Generated automatically by Doxygen for LAPACK from the source code\&.