CUDA C++ API#

Defines the CUDA API for sphericart.

namespace cuda#

The sphericart::cuda namespace contains the CUDA API for sphericart.

template<typename T>
class SphericalHarmonics#
#include <sphericart_cuda.hpp>

A spherical harmonics calculator.

It handles initialization of the prefactors upon initialization and it stores the buffers that are necessary to compute the spherical harmonics efficiently.

Public Functions

SphericalHarmonics(size_t l_max, bool normalized = false)#

Initialize the SphericalHarmonics class setting maximum degree and normalization

Parameters:

  • l_max – The maximum degree of the spherical harmonics to be calculated.

  • normalized – If false (default) computes the scaled spherical harmonics, which are homogeneous polynomials in the Cartesian coordinates of the input points. If true, computes the normalized spherical harmonics that are evaluated on the unit sphere. In practice, this simply computes the scaled harmonics at the normalized coordinates \((x/r, y/r, z/r)\), and adapts the derivatives accordingly.

void compute(const T *xyz, size_t nsamples, bool compute_with_gradients, bool compute_with_hessian, T *sph, T *dsph = nullptr, T *ddsph = nullptr, void *cuda_stream = nullptr)#

Computes the spherical harmonics for one or more 3D points, using pre-allocated device-side pointers

Parameters:

  • xyz – A pre-allocated device-side array of size n_samples x 3. It contains the Cartesian coordinates of the 3D points for which the spherical harmonics are to be computed, organized along two dimensions. The outer dimension is n_samples long, accounting for different samples, while the inner dimension has size 3 and it represents the x, y, and z coordinates respectively.

  • nsamples – Number of samples contained within xyz.

  • compute_with_gradients – Whether we should compute dsph. If true, the pointer dsph must also be allocated on device.

  • compute_with_hessians – Whether we should compute ddsph. If true, the pointer ddsph must also be allocated on device.

  • sph – On entry, a preallocated device-side array of size n_samples

  • dsph – On entry, nullptr or a preallocated device-side array of size . If the pointer is not nullptr, then compute_with_gradients must also be true in order for gradients to be computed.

  • ddsph – On entry, nullptr or a preallocated device-side array of size . If the pointer is not nullptr, then compute_with_hessians must also be true in order for gradients to be computed.

  • cuda_stream – Pointer to a cudaStream_t or nullptr. If this is nullptr, the kernel launch will be performed on the default stream.