main.cpp File Reference

2D Ising model – classic mode + nucleation with umbrella sampling More...

#include "numerics.hpp"
#include "stats/stats.hpp"
#include "analysis/roots.hpp"
#include "stochastic/markov.hpp"
#include "spatial/pbc_lattice.hpp"
#include "spatial/connected_components.hpp"
#include <raylib.h>
#include <cmath>
#include <random>
#include <vector>
#include <algorithm>
#include <cstring>

Go to the source code of this file.

Classes
struct	RingBuffer
struct	IsingLattice

Functions
int	main ()

Detailed Description

2D Ising model – classic mode + nucleation with umbrella sampling

Absorbs ~/projects/IsingNucleation into the numerics project. Exact match to IsingNucleation parameters: n=300, J=1, beta=0.58 (T~=1.724), F=0.1 (nucleation), F=0 (classic) Random spin selection per sweep (n^2 picks with replacement) DeltaE = 2J*s*(Sigma nbrs) - 2F*s (same sign convention as mc_step_boltz.c)

Optimizations vs. the original C implementation:

1. Boltzmann lookup table – DeltaE discrete -> precomputed exp() table, no runtime exp() in the sweep hot path
2. Precomputed neighbor arrays – up/dn/lt/rt[NN] avoid repeated modulo arithmetic per spin selection
3. Array-based BFS cluster detection – iterative, pre-allocated flat queue; no recursion stack risk, no heap allocations per call
4. SparseMatrix adj retained for energy_per_spin() (SIMD sparse_matvec)

Two modes (TAB to switch): Classic – free Metropolis; magnetisation and E/N^2 graphs Nucleation – umbrella sampling; tracks largest spin-down cluster (nucleus)

Definition in file main.cpp.

Function Documentation

main()

int main

(

)

Definition at line 290 of file main.cpp.

References IsingLattice::all_up(), RingBuffer::back(), IsingLattice::beta, num::RunningStats::count, IsingLattice::energy_per_spin(), IsingLattice::F, num::Histogram::fill(), IsingLattice::generate_nucleus(), num::ClusterResult::id, num::ClusterResult::largest_id, IsingLattice::magnetization(), num::RunningStats::mean, IsingLattice::mean_field_m(), RingBuffer::push(), IsingLattice::random_init(), num::RunningStats::reset(), num::Histogram::reset(), IsingLattice::set_field(), IsingLattice::set_temperature(), IsingLattice::spins, num::RunningStats::std_dev(), IsingLattice::sweep(), IsingLattice::sweep_umbrella(), and num::RunningStats::update().