gesvd_scratchpad_size#

Computes size of scratchpad memory required for gesvd function.

Description

gesvd_scratchpad_size supports the following precisions.

T

float

double

std::complex<float>

std::complex<double>

Computes the number of elements of type T the scratchpad memory to be passed to gesvd function should be able to hold. Calls to this routine must specify the template parameter explicitly.

gesvd_scratchpad_size#

Syntax

namespace oneapi::mkl::lapack {
  template <typename T>
  std::int64_t gesvd_scratchpad_size(cl::sycl::queue &queue, oneapi::mkl::job jobu, oneapi::mkl::job jobvt, std::int64_t m, std::int64_t n, std::int64_t lda, std::int64_t ldu, std::int64_t ldvt)
}

Input Parameters

queue

Device queue where calculations by gesvd function will be performed.

jobu

Must be job::allvec, job::somevec, job::overwritevec, or job::novec. Specifies options for computing all or part of the matrix \(U\).

If jobu = job::allvec, all \(m\) columns of \(U\) are returned in the buffer u;

if jobu = job::somevec, the first \(\min(m, n)\) columns of \(U\) (the left singular vectors) are returned in the buffer v;

if jobu = job::overwritevec, the first \(\min(m, n)\) columns of \(U\) (the left singular vectors) are overwritten on the buffer a;

if jobu = job::novec, no columns of \(U\) (no left singular vectors) are computed.

jobvt

Must be job::allvec, job::somevec, job::overwritevec, or job::novec. Specifies options for computing all or part of the matrix \(V^T/V^H\).

If jobvt = job::allvec, all \(n\) columns of \(V^T/V^H\) are returned in the buffer vt;

if jobvt = job::somevec, the first \(\min(m, n)\) columns of \(V^T/V^H\) (the left singular vectors) are returned in the buffer vt;

if jobvt = job::overwritevec, the first \(\min(m, n)\) columns of \(V^T/V^H\) (the left singular vectors) are overwritten on the buffer a;

if jobvt = job::novec, no columns of \(V^T/V^H\) (no left singular vectors) are computed.

m

The number of rows in the matrix \(A\) (\(0 \le m\)).

n

The number of columns in the matrix \(A\) (\(0 \le n\)).

lda

The leading dimension of a.

ldu

The leading dimension of u.

ldvt

The leading dimension of vt.

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::mkl::unimplemented

oneapi::mkl::unsupported_device

oneapi::mkl::lapack::invalid_argument

Exception is thrown in case of incorrect supplied argument value. Position of wrong argument can be determined by info() method of exception object.

Return Value

The number of elements of type T the scratchpad memory to be passed to gesvd function should be able to hold.

Parent topic: LAPACK Singular Value and Eigenvalue Problem Routines