sr_beverton_holt.hpp

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#ifndef FIMS_POPULATION_DYNAMICS_RECRUITMENT_SR_BEVERTON_HOLT_HPP
#define FIMS_POPULATION_DYNAMICS_RECRUITMENT_SR_BEVERTON_HOLT_HPP
 
#include "recruitment_base.hpp"
#include "common/fims_vector.hpp"
 
namespace fims_popdy {

template <typename Type>
struct SRBevertonHolt : public RecruitmentBase<Type> {
  // Here we define the members that will be used in the Beverton--Holt
  // stock--recruitment function. These members are needed by the Beverton--Holt
  // stock--recruitment function but will not be common to all recruitment
  // functions.
  fims::Vector<Type> logit_steep; 
 
  SRBevertonHolt() : RecruitmentBase<Type>() {}
 
  virtual ~SRBevertonHolt() {}

  virtual const Type evaluate_mean(const Type& spawners, const Type& phi_0) {
    Type recruits;
    Type steep;
    Type steep_lo = static_cast<Type>(0.2);
    Type steep_hi = static_cast<Type>(1.0);
    Type rzero;
 
    // Transform input parameters
    steep = fims_math::inv_logit(steep_lo, steep_hi, this->logit_steep[0]);
    rzero = fims_math::exp(this->log_rzero[0]);
 
    recruits = (static_cast<Type>(0.8) * rzero * steep * spawners) /
               (static_cast<Type>(0.2) * phi_0 * rzero *
                    (static_cast<Type>(1.0) - steep) +
                spawners * (steep - static_cast<Type>(0.2)));
 
    return recruits;
  }

  virtual const Type evaluate_process(size_t pos) { return 0; }
};
 
}  // namespace fims_popdy
 
#endif /* FIMS_POPULATION_DYNAMICS_RECRUITMENT_SR_BEVERTON_HOLT_HPP */