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#pragma once
#include <cmath>
#include <stdio.h>
#include <wolff/types.h>
// all that is required to use wolff.hpp is a default constructor
class ising_t {
public:
bool x;
ising_t() : x(false) {}
// optional constructors for syntactic sugar
ising_t(bool x) : x(x) {}
ising_t(int x) : x((bool)x) {}
/* below this comment is code required only for using measure.hpp in the
* examples folder, which provides an interface for measuring several
* generic features of models. these require
*
* - an M_t, representing the magnetization or sum of all spins
* - an F_t, representing a double-weighted version of the magnetization
* - the overloaded operator *, which takes a v_t (unsigned int) and returns an M_t
* - the overloaded operator *, which takes a double and returns an F_t
* - the overloaded operator -, which takes another X_t and returns an M_t
*/
typedef int M_t;
typedef double F_t;
inline int operator*(v_t a) const {
if (x) {
return -(int)a;
} else {
return (int)a;
}
}
inline double operator*(double a) const {
if (x) {
return -a;
} else {
return a;
}
}
inline int operator-(const ising_t &s) const {
if (x == s.x) {
return 0;
} else {
if (x) {
return -2;
} else {
return 2;
}
}
}
};
/* using measure.hpp additionally requires a norm_squared function which takes
* an F_t to a double, and a write_magnetization function, which takes an M_t
* and a FILE pointer and appropriately records the contents of the former to
* the latter.
*/
double norm_squared(double s) {
return pow(s, 2);
}
void write_magnetization(int M, FILE *outfile) {
fwrite(&M, sizeof(int), 1, outfile);
}
/* these definitions allow wolff/finite_states.hpp to be invoked and provide
* much faster performance for models whose number of possible spin
* configurations is finite.
*/
#define N_STATES 2
const ising_t states[2] = {ising_t(0), ising_t(1)};
q_t state_to_ind(ising_t state) { return (q_t)state.x; }
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