<cuda/std/complex>#

2026-10-01

3 min read time

Applies to Linux and Windows

This page documents the cuda::std::complex support in libhipcxx, including omissions for long double and literals with NVCC, and extensions for infinity handling and half/bfloat16 types.

Omissions#

When using libhipcxx with NVCC, complex does not support long double or complex literals (_i, _if, and _il). NVCC warns on any usage of long double in device code, because long double will be demoted to double in device code. This warning can be suppressed silenced with #pragmas, but only globally, not just when using complex. User-defined floating-point literals must be specified in terms of long double, so they lead to warnings that are unable to be suppressed.

Extensions#

  • Handling of infinities

    Our implementation by default recovers infinite values during multiplication and division. This adds a significant runtime overhead, so we allow disabling that canonicalization if it is not desired.

    Definition of LIBCUDACXX_ENABLE_SIMPLIFIED_COMPLEX_OPERATIONS disables canonicalization for both multiplication and division.

    Definition of LIBCUDACXX_ENABLE_SIMPLIFIED_COMPLEX_MULTIPLICATION or LIBCUDACXX_ENABLE_SIMPLIFIED_COMPLEX_DIVISION disables canonicalization for multiplication or division individually.

  • Support for half and bfloat16 (since libhipcxx 2.4.0)

    Our implementation includes support for the __half type from <cuda_fp16.h>, when the CUDA toolkit version is at least 12.2, and when CCCL_DISABLE_FP16_SUPPORT is not defined.

    This is detected automatically when compiling through NVCC. If you are compiling a host-only translation unit directly with the host compiler, you must define the macro LIBCUDACXX_ENABLE_HOST_NVFP16 prior to including any libhipcxx headers, and you must ensure that the <cuda_fp16.h> header that’s found by the compiler comes from a CUDA toolkit version 12.2 or higher.

    Our implementation includes support for the __nv_bfloat16 type from <cuda_bf16.h>, when the conditions for the support of __half are fulfilled, and when CCCL_DISABLE_BF16_SUPPORT and CCCL_DISABLE_FP16_SUPPORT are not defined.

  • C++20 constexpr <complex> is available in C++14.

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