+#ifndef SIM_HPP
+#define SIM_HPP
+
+#include <gsl/gsl_rng.h>
+#include <complex>
+#include <math.h>
+
+#include "latlib/neigh.h"
+
+class sim : public o815::sim {
+public:
+ struct siteconf {
+ complex<double> phi;
+ };
+ sim(o815 *_O815);
+ siteconf* conf;
+ unsigned int LSIZE2;
+ double M;
+ double m;
+ neigh *nb;
+
+private:
+ void _makeSweep();
+ void _newParas();
+ gsl_rng* rangsl;
+ void updatePhi (const int& x);
+};
+
+
+
+sim::sim(o815 *_O815) : o815::sim( _O815,
+ sizeof(siteconf)*
+ (_O815->comargs.lsize[0]*_O815->comargs.lsize[1]) ) {
+ conf = (siteconf*)confMem;
+
+ rangsl = gsl_rng_alloc(gsl_rng_ranlxs0);
+ gsl_rng_set(rangsl, time(NULL));
+
+ LSIZE2 = _O815->comargs.lsize[0] * _O815->comargs.lsize[1];
+
+ nb = new neigh(2, _O815->comargs.lsize[0], _O815->comargs.lsize[1]);
+}
+
+void sim::updatePhi (const int& x)
+{
+ const double r = gsl_rng_uniform(rangsl);
+ complex<double> V=0;
+
+ for (int nu=0; nu<4; nu++)
+ V += conf[ (*nb)[x*4+nu] ].phi;
+
+ const double V2diff = pow(real(V), 2) - pow(imag(V), 2);
+ const double Vprod = real(V)*imag(V);
+ conf[x].phi = complex<double> ( + real(conf[x].phi) * V2diff + 2 * imag(conf[x].phi) * Vprod,
+ - imag(conf[x].phi) * V2diff + 2 * real(conf[x].phi) * Vprod ) / norm(V);
+
+ conf[x].phi = sqrt(std::log( 1./(1-r) )) / sqrt(M)
+ * polar(1.0, gsl_rng_uniform(rangsl) * 2*M_PI)
+ + V / M;
+}
+
+void sim::_makeSweep() {
+ for (int ichecker=0; ichecker<2; ichecker++)
+ for (int it=0; it<O815->comargs.lsize[0]; it++)
+ for (int iy=(it+ichecker)%2; iy<O815->comargs.lsize[1]; iy+=2)
+ updatePhi( it*O815->comargs.lsize[1] + iy );
+}
+
+void sim::_newParas() {
+ m = (*O815->paraQ)["mass"];
+ M = pow( (*O815->paraQ)["mass"], 2 ) + 4;
+ *log << "SIM: Resetting fields." << endl << flush;
+
+ for (int ix=0; ix<LSIZE2; ix++)
+ conf[ix].phi = 1;
+}
+
+#endif