EigenLib.h

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#pragma once

#include "Numerics.h"

// turn off warnings for the rest of this
#pragma GCC system_header

// This is just a header to include Eigen, but preven us from warning about it. 
#include <cmath>
#include <eigen3/Eigen/Core>
#include <eigen3/Eigen/Dense>
#include <eigen3/Eigen/Eigenvalues> 
#include <eigen3/unsupported/Eigen/SpecialFunctions>
#include "IO.h"

// Define some useful names here 
using Vector = Eigen::VectorXf; 
using Matrix = Eigen::MatrixXf; 

// Woah this is WAAAY slower
//double logsumexp(const Vector& v) {
//  
//  double lse = -infinity;
//  for(int i=0;i<v.size();i++) {
//      lse = logplusexp((double)v(i), lse);
//  }
//  return lse;
//}

double logsumexp_eigen(const Vector& v) {
    double mx = v.maxCoeff();
    return log((v.array()-mx).array().exp().sum()) + mx;
}

Vector lognormalize(const Vector& v) {
    return v.array() - logsumexp_eigen(v);
}

Vector eigenslice(const Vector& v, const size_t offset, const size_t len) {
    Vector out(len);
    for(size_t i=0;i<len;i++) {
        out(i) = v[i+offset];
    }
    return out;
}

// And we define a macro so that other code in fleet can optionally include Eigen-compatible 
// operations.
// NOTE that this requires us to include EigenLib before we import anything else (e.g. grammar)
#define AM_I_USING_EIGEN 1