log.hpp

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#ifndef STAN__AGRAD__REV__FUNCTIONS__LOG_HPP
#define STAN__AGRAD__REV__FUNCTIONS__LOG_HPP

#include <cmath>
#include <stan/agrad/rev/var.hpp>
#include <stan/agrad/rev/internal/v_vari.hpp>

namespace stan {
  namespace agrad {

    namespace {
      class log_vari : public op_v_vari {
      public:
        log_vari(vari* avi) :
          op_v_vari(std::log(avi->val_),avi) {
        }
        void chain() {
          avi_->adj_ += adj_ / avi_->val_;
        }
      };
    }

    inline var log(const var& a) {
      return var(new log_vari(a.vi_));
    }
    
  }
}
#endif