Function

# cblas_dtbmv

Scales a triangular band matrix, then multiplies by a vector (double precision).

## Parameters

`Order`

Specifies row-major (C) or column-major (Fortran) data ordering.

`Uplo`

Specifies whether to use the upper or lower triangle from the matrix. Valid values are `'U'` or `'L'`.

`TransA`

Specifies whether to use matrix A (`'N'` or `'n'`) or the transpose of A (`'T'`, `'t'`, `'C'`, or `'c'`).

`Diag`

Specifies whether the matrix is unit triangular. Possible values are `'U'` (unit triangular) or `'N'` (not unit triangular).

`N`

The order of matrix `A`.

`K`

Half-bandwidth of matrix `A`.

`A`

Matrix `A`.

`lda`

The leading dimension of array containing matrix `A`.

`X`

Vector `x`.

`incX`

Stride within `X`. For example, if `incX` is 7, every 7th element is used.

## Discussion

Computes `A*x` and stores the results in `x`.

### Double-Precision Float Matrix Functions

`cblas_dasum`

Computes the sum of the absolute values of elements in a vector (double-precision).

`cblas_daxpy`

Computes a constant times a vector plus a vector (double-precision).

`cblas_dcopy`

Copies a vector to another vector (double-precision).

`cblas_dgbmv`

Scales a general band matrix, then multiplies by a vector, then adds a vector (double precision).

`cblas_dgemm`

Multiplies two matrices (double-precision).

`cblas_dgemv`

Multiplies a matrix by a vector (double precision).

`cblas_dger`

Multiplies vector X by the transpose of vector Y, then adds matrix A (double precison).

`cblas_dnrm2`

Computes the L2 norm (Euclidian length) of a vector (double precision).

`cblas_drot`

Applies a Givens rotation matrix to a pair of vectors.

`cblas_drotg`

Constructs a Givens rotation matrix.

`cblas_drotm`

Applies a modified Givens transformation (single precision).

`cblas_drotmg`

Generates a modified Givens rotation matrix.

`cblas_dsbmv`

Scales a symmetric band matrix, then multiplies by a vector, then adds a vector (double precision).

`cblas_dscal`

Multiplies each element of a vector by a constant (double-precision).

`cblas_dspmv`

Scales a packed symmetric matrix, then multiplies by a vector, then scales and adds another vector (double precision).

`cblas_dspr`

Rank one update: adds a packed symmetric matrix to the product of a scaling factor, a vector, and its transpose (double precision).

`cblas_dspr2`

Rank two update of a packed symmetric matrix using two vectors (single precision).

`cblas_dswap`

Exchanges the elements of two vectors (double precision).

`cblas_dsymm`

Multiplies a matrix by a symmetric matrix (double-precision).

`cblas_dsymv`

Scales a symmetric matrix, multiplies by a vector, then scales and adds another vector (single precision).

`cblas_dsyr`

Rank one update: adds a symmetric matrix to the product of a scaling factor, a vector, and its transpose (double precision).

`cblas_dsyr2`

Rank two update of a symmetric matrix using two vectors (single precision).

`cblas_dsyr2k`

Performs a rank-2k update of a symmetric matrix (double precision).

`cblas_dsyrk`

Rank-k update—multiplies a symmetric matrix by its transpose and adds a second matrix (double precision).

`cblas_dtbsv`

Solves a triangular banded system of equations.

`cblas_dtpmv`

Multiplies a triangular matrix by a vector, then adds a vector (double precision).

`cblas_dtpsv`

Solves a packed triangular system of equations.

`cblas_dtrmm`

Scales a triangular matrix and multiplies it by a matrix.

`cblas_dtrmv`

Multiplies a triangular matrix by a vector.

`cblas_dtrsm`

Solves a triangular system of equations with multiple values for the right side.

`cblas_dtrsv`

Solves a triangular system of equations with a single value for the right side.