Data Types

oneMKL - Data Parallel C++ Developer Reference

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Date 10/31/2024

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Data Types

BLAS and LAPACK Data Types

Intel® oneAPI Math Kernel Library (oneMKL) BLAS and LAPACK for Data Parallel C++ (DPC++) introduces several new enumeration data types, which are type-safe versions of the traditional Fortran characters in BLAS and LAPACK. They are declared in oneapi/mkl/types.hpp, which is included automatically when you include oneapi/mkl/blas.hpp or oneapi/mkl/lapack.hpp. Like all oneMKL DPC++ functionality, they belong to the namespace oneapi::mkl::.

Each enumeration value comes with two names: A single-character name (the traditional BLAS/LAPACK character) and a longer, descriptive name. The two names are exactly equivalent and may be used interchangeably.

Transpose

The transpose type specifies whether an input matrix should be transposed and/or conjugated. It can take the following values:

Short Name	Long Name	Description
`transpose::N`	`transpose::nontrans`	Do not transpose or conjugate the matrix.
`transpose::T`	`transpose::trans`	Transpose the matrix.
`transpose::C`	`transpose::conjtrans`	Perform Hermitian transpose (transpose and conjugate). Only applicable to complex matrices.

Uplo

The uplo type specifies whether the lower or upper triangle of a triangular, symmetric, or Hermitian matrix should be accessed. It can take the following values:

Short Name	Long Name	Description
`uplo::U`	`uplo::upper`	Access the upper triangle of the matrix.
`uplo::L`	`uplo::lower`	Access the lower triangle of the matrix.

In both cases, elements that are not in the selected triangle are not accessed or updated.

Diag

The diag type specifies the values on the diagonal of a triangular matrix. It can take the following values:

Short Name	Long Name	Description
`diag::N`	`diag::nonunit`	The matrix is not unit triangular. The diagonal entries are stored with the matrix data.
`diag::U`	`diag::unit`	The matrix is unit triangular (the diagonal entries are all 1s). The diagonal entries in the matrix data are not accessed.

Side

The side type specifies the order of matrix multiplication when one matrix has a special form (triangular, symmetric, or Hermitian):

Short Name	Long Name	Description
`side::L`	`side::left`	The special form matrix is on the left in the multiplication.
`side::R`	`side::right`	The special form matrix is on the right in the multiplication.

Offset

The offset type specifies whether the offset to apply to an output matrix is a fix offset, column offset or row offset. It can take the following values

Short Name	Long Name	Description
`offset::F`	`offset::fix`	The offset to apply to the output matrix is fix, all the inputs in the `C_offset` matrix has the same value given by the first element in the `co` array.
`offset::C`	`offset::column`	The offset to apply to the output matrix is a column offset, that is to say all the columns in the `C_offset` matrix are the same and given by the elements in the `co` array.
`offset::R`	`offset::row`	The offset to apply to the output matrix is a row offset, that is to say all the rows in the `C_offset` matrix are the same and given by the elements in the `co` array.

value_or_pointer

The value_or_pointer type is used as a wrapper to enable users to pass either a pointer or a value to BLAS routines that take scalar parameters (usually named alpha or beta). Its use is described in Scalar Arguments.

Vector Math Data Types

oneMKL VM for Data Parallel C++ (DPC++) introduces a slice type, available in the oneapi::mkl namespace. Slices are used in the DPC++ VM Strided APIs. oneMKL slices accept positive, zero, and negative strides, for forward, static, and backward traversals of a vector, respectively.

Constructors	Description
slice()	Default constructor equivalent to slice(0, 0, 0).
slice(`std::size_tstart`, `std::size_tsize`, `std::int64_tstride`)	Slice defining the start index, the number of values to select, and the stride between two elements.
slice(`constslice& other`)	Copy constructor.

For example:

slice(1, 5, 2) defines a selector of elements at indices 1, 3, 5, 7, 9 in a buffer or array;
slice(0, 5, 0) defines a selector of a single element at index 0, repeated five times;
slice(9, 4, -3) defines a selector of elements at indices 9, 6, 3, 0.

A slice is considered invalid if it produces negative indices. A slice of size 0 selects no element. If a slice may cause out-of-bounds memory accesses, the behavior is undefined.

The behavior of VM Strided APIs used with invalid or non-equal slices is configurable with several oneMKL VM mode values. See the set_mode function for possible values and their descriptions.

In the slice_cyclic mode, zero-sized slices are invalid.

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oneMKL - Data Parallel C++ Developer Reference

Data Types

BLAS and LAPACK Data Types

Vector Math Data Types