abs.hpp

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#ifndef __STAN__AGRAD__REV__ABS_HPP__
#define __STAN__AGRAD__REV__ABS_HPP__

#include <stan/agrad/rev/var.hpp>
#include <stan/agrad/rev/vari.hpp>
#include <stan/agrad/rev/operator_unary_negative.hpp>

namespace stan {
  namespace agrad {

    inline var abs(const var& a) {   
      // cut-and-paste from fabs()
      if (a.val() > 0.0)
        return a;
      if (a.val() < 0.0)
        return var(new neg_vari(a.vi_));
      // FIXME:  same as fabs() -- is this right?
      return var(new vari(0.0));
    }

  }
}
#endif