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#ifndef _QUASI_MODEL2_H_
#define _QUASI_MODEL2_H_
#include <vector>
#include <cmath>
#include "prob.h"
#include "array2d.h"
struct QuasiModel2 {
explicit QuasiModel2(double alpha, double pnull = 0.1) :
alpha_(alpha),
pnull_(pnull),
pnotnull_(1 - pnull),
z_(1000,1000) {}
// a_j = 0 => NULL; src_len does *not* include null
prob_t Pa_j(unsigned a_j, unsigned j, unsigned src_len, unsigned trg_len) const {
if (!a_j) return pnull_;
std::vector<prob_t>& zv = z_(src_len, trg_len);
if (zv.size() == 0)
zv.resize(trg_len);
prob_t& z = zv[j];
if (z.is_0()) z = ComputeZ(j, src_len, trg_len);
prob_t p;
p.logeq(-fabs(double(a_j - 1) / src_len - double(j) / trg_len) * alpha_);
p *= pnotnull_;
p /= z;
return p;
}
private:
prob_t ComputeZ(unsigned j, unsigned src_len, unsigned trg_len) const {
prob_t p, z = prob_t::Zero();
for (int a_j = 1; a_j <= src_len; ++a_j) {
p.logeq(-fabs(double(a_j - 1) / src_len - double(j) / trg_len) * alpha_);
z += p;
}
return z;
}
double alpha_;
const prob_t pnull_;
const prob_t pnotnull_;
mutable Array2D<std::vector<prob_t> > z_;
};
#endif
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