STBMV/DTBMV/CTBMV/ZTBMV

Matrix-vector multiply

 

’U’ or ’u’

A is upper triangular

trans

Transposition option for A:

 

’N’ or ’n’

Compute x ← Ax

 

’T’ or ’t’

Compute x ← ATx

 

’C’ or ’c’

Compute x ← A*x

 

where AT is the transpose of A, and A* is the conjugate

 

transpose. In the real subprograms, ’C’ and ’c’ have the

 

same meaning as ’T’ and ’t’.

diag

Specifies whether the matrix is unit triangular, that is,

 

aii = 1, or not:

 

 

’N’ or ’n’

The diagonal of A is stored in the

 

 

array

 

’U’ or ’u’

The diagonal of A consists of unstored

 

 

ones

 

When diag is supplied as ’U’ or ’u’, diagonal elements of

 

A are not referenced, but space must be reserved for

 

them.

 

n

Number of rows and columns in matrix A, n ≥ 0. If n =

 

0, the subprograms do not reference ab or x.

kd

The number of nonzero diagonals above or below the

 

principal diagonal. If uplo is supplied as ’U’ or ’u’, kd

 

specifies the number of nonzero diagonals above the

 

principal diagonal. If uplo is supplied as ’L’ or ’l’, kd

 

specifies the number of nonzero diagonals below the

 

principal diagonal.

ab

Array containing the n-by-ntriangular band matrix A

 

in the compressed form described above. The columns

 

of the band of A are stored in the columns of ab, and

 

the diagonals of the band of A are stored in the rows of

 

ab.

 

ldab

The leading dimension of array ab as declared in the

 

calling program unit, with ldab ≥ kd+1.

x

Array of length lenx = (n−1)⋅incx+1 containing the

 

input vector x.

 

incx

Increment for the array x, incx ≠ 0:

 

incx > 0

x is stored forward in array x; that is,

 

 

xi is stored in x((i−1)⋅incx+1).

298HP MLIB User’s Guide