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Visible to Intel only — GUID: GUID-BF0E436B-F611-4AAF-A600-753180E782B3
Visible to Intel only — GUID: GUID-BF0E436B-F611-4AAF-A600-753180E782B3
ungqr_batch (Buffer Strided Version)
Generates the complex unitary matrices Qi of the batch of QR factorizations formed by geqrf_batch function (Buffer stride version). This routine belongs to the oneapi::mkl::lapack namespace.
Description
The routine generates the wholes or parts of m-by-m unitary matrix Qi of the QR factorization formed by the geqrf_batch (Buffer Strided Version) function.
Usually Qi is determined from the QR factorization of an m by p matrix Ai with m ≥ p. To compute the whole matrices Qi, use:
ungqr_batch(queue, m, m, p, a, ...)
To compute the leading p columns of Qi (which form an orthonormal basis in the space spanned by the columns of Ai):
ungqr_batch(queue, m, p, p, a, ...)
To compute the matrix Qik of the QR factorization of the leading k columns of the matrices Ai:
ungqr_batch(queue, m, m, k, a, ...)
To compute the leading k columns of Qik (which form an orthonormal basis in the space spanned by the leading k columns of the matrices Ai):
ungqr_batch(queue, m, k, k, a, ...)
API
Syntax
namespace oneapi::mkl::lapack { void ungqr_batch(sycl::queue &queue, std::int64_t m, std::int64_t n, std::int64_t k, sycl::buffer<T> &a, std::int64_t lda, std::int64_t stride_a, sycl::buffer<T> &tau, std::int64_t stride_tau, std::int64_t batch_size, sycl::buffer<T> &scratchpad, std::int64_t scratchpad_size) }
This function supports the following precisions and devices:
T |
Devices supported |
|---|---|
std::complex<float> |
CPU and GPU* |
std::complex<double> |
CPU and GPU* |
*Interface support only; all computations are performed on the CPU.
Input Parameters
- queue
-
Device queue where calculations will be performed.
- m
-
The number of rows in the matrices Ai (m ≥ 0).
- n
-
The number of columns in the matrices Ai (n ≥ 0).
- k
-
the number of elementary reflectors whose product defines the matrices Qi (0 ≤ k ≤ n) .
- a
-
Array resulting after a call to geqrf_batch (Buffer Strided Version).
- lda
-
The leading dimension of Ai (lda ≥ max(1,m)).
- stride_a
-
The stride between the beginnings of matrices Ai inside the batch array a (stride_a ≥ max(1, lda * n)).
- tau
-
Array resulting after a call to geqrf_batch (Buffer Strided Version).
- stride_tau
-
The stride between the beginnings of arrays taui inside the array tau (stride_tau ≥ max(1, min(m,n))).
- batch_size
-
The number of problems in a batch (batch_size ≥ 0).
- scratchpad
-
Scratchpad memory to be used by routine for storing intermediate results.
- scratchpad_size
-
Size of scratchpad memory as a number of floating point elements of type T. Size should not be less than the value returned by ungqr_batch_scratchpad_size (Strided Version).
Output Parameters
- a
-
Array data is overwritten by a batch of n leading columns of the m-by-m unitary matrices Qi.
Exceptions
Exception |
Description |
|---|---|
mkl::lapack::batch_exception |
This exception is thrown when problems occur during calculations. You can obtain the info code of the problem using the info() method of the exception object: If info = -n, the n-th parameter had an illegal value. If info equals the value passed as scratchpad size, and detail() returns non-zero, then the passed scratchpad is of insufficient size, and the required size should be not less then value returned by the detail() method of the exception object. |