rocSOLVER precision support

rocSOLVER precision support#

This section provides an overview of the numerical precision types supported by the rocSOLVER library.

Supported precision types#

rocSOLVER supports four primary precision types across its functions:

Type prefix

C++ type

Description

s

float

Single-precision real (32-bit)

d

double

Double-precision real (64-bit)

c

rocblas_float_complex

Single-precision complex (32-bit real, 32-bit imaginary)

z

rocblas_double_complex

Double-precision complex (64-bit real, 64-bit imaginary)

Function naming convention#

rocSOLVER follows the standard LAPACK naming convention where the first letter of the function name indicates the precision type:

  • Functions beginning with rocsolver_s operate on single-precision real data.

  • Functions beginning with rocsolver_d operate on double-precision real data.

  • Functions beginning with rocsolver_c operate on single-precision complex data.

  • Functions beginning with rocsolver_z operate on double-precision complex data.

For example, the LU factorization function getrf is implemented as:

  • rocsolver_sgetrf - For single-precision real matrices

  • rocsolver_dgetrf - For double-precision real matrices

  • rocsolver_cgetrf - For single-precision complex matrices

  • rocsolver_zgetrf - For double-precision complex matrices

In the documentation, these are often represented generically as rocsolver_<type>getrf(), where <type> is a placeholder for the precision type prefix.

Understanding precision in function signatures#

In the function signatures throughout the documentation, precision information is indicated directly in the parameter types. For example:

rocblas_status rocsolver_slarfb(rocblas_handle handle, /* ... */
                                float *v, /* ... */
                                float *t, /* ... */
                                float *a, /* ... */)

The parameter types (float, double, rocblas_float_complex, or rocblas_double_complex) correspond to the function prefix and indicate the precision used by that specific function variant.

Real versus complex precision#

Some LAPACK functions have different behaviors or names when operating on real versus complex data:

  • Functions for symmetric matrices (prefix sy) use the same name for both real precision types.

  • Functions for Hermitian matrices (prefix he) are used for complex precision types.

  • Some auxiliary routines might be specific to real or complex precision types.

For example, rocsolver_ssytrd and rocsolver_dsytrd handle real symmetric matrices, while rocsolver_chetrd and rocsolver_zhetrd handle complex Hermitian matrices.