anchor.diff:  
       real(real64), intent(in) :: alpha
   
  -    log_fwa = (log_fpa(alpha) - log_fpa_amax) + (log_fpxa(alpha) - log_fpxa_amax)
  +    log_fwa = log_fpa(alpha) + log_fpxa(alpha)
   
     end function log_fwa
   
  
positive.code:     real(real64) :: a
  
      a = exp(x)
      m_func = exp(log_fwa(a)) * hdir(a) * a
      
    end function m_func
  
  
negative.code:     
      fxs = log_fwa(xs)
      amax = xs(maxloc(fxs,1,fxs < largest))
      log_fwa_amax = log_fwa(amax)
      
    end subroutine compute_integration_range
  
  