rotg#

Computes the parameters for a Givens rotation.

Description

Given the Cartesian coordinates (a, b) of a point, the rotg routines return the parameters c, s, r, and z associated with the Givens rotation. The parameters c and s define a unitary matrix such that:

\[\begin{split}\begin{bmatrix}c & s \\ -s & c\end{bmatrix}. \begin{bmatrix}a \\ b\end{bmatrix} =\begin{bmatrix}r \\ 0\end{bmatrix}\end{split}\]

The parameter z is defined such that if |a| > |b|, z is s; otherwise if c is not 0 z is 1/c; otherwise z is 1.

rotg supports the following precisions.

T

Tc

float

float

double

double

std::complex<float>

float

std::complex<double>

double

T	Tc
`float`	`float`
`double`	`double`
`std::complex<float>`	`float`
`std::complex<double>`	`double`

rotg (Buffer Version)#

Syntax

namespace oneapi::math::blas::column_major {
    void rotg(sycl::queue &queue,
              sycl::buffer<T,1> &a,
              sycl::buffer<T,1> &b,
              sycl::buffer<Tc,1> &c,
              sycl::buffer<T,1> &s)
}

namespace oneapi::math::blas::row_major {
    void rotg(sycl::queue &queue,
              sycl::buffer<T,1> &a,
              sycl::buffer<T,1> &b,
              sycl::buffer<Tc,1> &c,
              sycl::buffer<T,1> &s)
}

Input Parameters

queue: The queue where the routine should be executed
a: Buffer holding the x-coordinate of the point.
b: Buffer holding the y-coordinate of the point.

Output Parameters

a: Buffer holding the parameter r associated with the Givens rotation.
b: Buffer holding the parameter z associated with the Givens rotation.
c: Buffer holding the parameter c associated with the Givens rotation.
s: Buffer holding the parameter s associated with the Givens rotation.

Throws

This routine shall throw the following exceptions if the associated condition is detected. An implementation may throw additional implementation-specific exception(s) in case of error conditions not covered here.

oneapi::math::invalid_argument

oneapi::math::unsupported_device

oneapi::math::host_bad_alloc

oneapi::math::device_bad_alloc

oneapi::math::unimplemented

rotg (USM Version)#

Syntax

namespace oneapi::math::blas::column_major {
    sycl::event rotg(sycl::queue &queue,
                     T *a,
                     T *b,
                     Tc *c,
                     T *s,
                     const std::vector<sycl::event> &dependencies = {})
}

namespace oneapi::math::blas::row_major {
    sycl::event rotg(sycl::queue &queue,
                     T *a,
                     T *b,
                     Tc *c,
                     T *s,
                     const std::vector<sycl::event> &dependencies = {})
}

Input Parameters

queue: The queue where the routine should be executed
a: Pointer to the x-coordinate of the point.
b: Pointer to the y-coordinate of the point.
dependencies: List of events to wait for before starting computation, if any. If omitted, defaults to no dependencies.