.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,
 'symbolically' zero components are not perturbed\&.  A zero
 entry is considered 'symbolic' 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\&.