Function

# cblas_drotm

Applies a modified Givens transformation (single precision).

## Parameters

`N`

Number of elements in vectors.

`X`

Vector `X`. Modified on return.

`incX`

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

`Y`

Vector `Y`. Modified on return.

`incY`

Stride within `Y`. For example, if `incY` is 7, every 7th element is used.

`P`

A 5-element vector:

`P[0]`

Flag value that defines the form of matrix `H`.

`-2.0`: matrix `H` contains the identity matrix.

`-1.0`: matrix `H` is identical to matrix `SH` (defined by the remaining values in the vector).

`0.0`: `H[1,2]` and `H[2,1]` are obtained from matrix `SH`. The remaining values are both `1.0`.

`1.0`: `H[1,1]` and `H[2,2]` are obtained from matrix `SH`. `H[1,2]` is 1.0. `H[2,1]` is -1.0.

`P[1]`

Contains `SH[1,1]`.

`P[2]`

Contains `SH[2,1]`.

`P[3]`

Contains `SH[1,2]`.

`P[4]`

Contains `SH[2,2]`.

### 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_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_dtbmv`

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