include/pops/numerics/linalg/lorentz_eliminator.hpp Source File

adc_cpp 0.3.0 Model-free C++23 core for coupled hyperbolic-elliptic systems on adaptive (AMR) meshes, with MPI and GPU (Kokkos) backends

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• linalg

lorentz_eliminator.hpp

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1

9

10#pragma once

11

12#include <pops/core/foundation/types.hpp>

13

14namespace pops {

15

55struct LorentzEliminator {

56 Real w; // w = theta * dt * B_z

57 Real det; // det(B) = 1 + w^2

58

59 // theta: implicitness of the scheme (0 = explicit, 1 = implicit, 0.5 = Crank-Nicolson).

60 // dt: time step.

61 // B_z: z component of the magnetic field.

63 POPS_HD LorentzEliminator(Real theta, Real dt, Real B_z)

64 : w(theta * dt * B_z), det(Real(1) + (theta * dt * B_z) * (theta * dt * B_z)) {}

65

67 POPS_HD void apply_B(Real vx, Real vy, Real& Bx, Real& By) const {

68 Bx = vx - w * vy;

69 By = vy + w * vx;

70 }

71

73 POPS_HD void apply_Binv(Real vx, Real vy, Real& vxp, Real& vyp) const {

74 const Real inv = Real(1) / det;

75 vxp = inv * (vx + w * vy);

76 vyp = inv * (vy - w * vx);

77 }

78

81 POPS_HD Real binv_11() const { return Real(1) / det; }

82 POPS_HD Real binv_12() const { return w / det; }

83 POPS_HD Real binv_21() const { return -w / det; }

84 POPS_HD Real binv_22() const { return Real(1) / det; }

86};

87

88// Static check: LorentzEliminator is trivially copyable (POD-like),

89// guaranteeing it can be captured by value in a Kokkos/CUDA kernel

90// without hidden allocation.

91static_assert(__is_trivially_copyable(LorentzEliminator),

92 "LorentzEliminator must be trivially copyable (zero allocation, device-safe)");

93

94} // namespace pops

pops

Definition amr_hierarchy.hpp:29

pops::Real

double Real

Definition types.hpp:30

pops::LorentzEliminator

LorentzEliminator: operator B = [[1,-w],[w,1]] and its analytic inverse.

Definition lorentz_eliminator.hpp:55

pops::LorentzEliminator::apply_B

POPS_HD void apply_B(Real vx, Real vy, Real &Bx, Real &By) const

apply_B: applies B = [[1,-w],[w,1]] to (vx, vy), writes (Bx, By). POPS_HD.

Definition lorentz_eliminator.hpp:67

pops::LorentzEliminator::binv_11

POPS_HD Real binv_11() const

Definition lorentz_eliminator.hpp:81

pops::LorentzEliminator::binv_21

POPS_HD Real binv_21() const

Definition lorentz_eliminator.hpp:83

pops::LorentzEliminator::binv_12

POPS_HD Real binv_12() const

Definition lorentz_eliminator.hpp:82

pops::LorentzEliminator::apply_Binv

POPS_HD void apply_Binv(Real vx, Real vy, Real &vxp, Real &vyp) const

apply_Binv: applies B^{-1} = (1/det)*[[1,w],[-w,1]] to (vx, vy), writes (vxp, vyp)....

Definition lorentz_eliminator.hpp:73

pops::LorentzEliminator::LorentzEliminator

POPS_HD LorentzEliminator(Real theta, Real dt, Real B_z)

Builds from (theta, dt, B_z): w = theta*dt*B_z, det = 1 + w^2. POPS_HD.

Definition lorentz_eliminator.hpp:63

pops::LorentzEliminator::w

Real w

Definition lorentz_eliminator.hpp:56

pops::LorentzEliminator::binv_22

POPS_HD Real binv_22() const

Definition lorentz_eliminator.hpp:84

pops::LorentzEliminator::det

Real det

Definition lorentz_eliminator.hpp:57

types.hpp

Base scalar types and the POPS_HD macro (host+device portability).

POPS_HD

#define POPS_HD

Definition types.hpp:25

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