anchor.diff:      real(real64) :: a
   
       a = exp(x)
  -    m2_func = exp(log_fwa(a)) * hdir(a)**2 * a
  +    m2_func = exp(log_fwa(a) - log_fwa_amax) * hdir(a)**2 * a
       
     end function m2_func
   
  
positive.code: 
      real(real64), intent(in) :: alpha
  
      log_fwa = (log_fpa(alpha) - log_fpa_amax) + (log_fpxa(alpha) - log_fpxa_amax)
  
    end function log_fwa
  
  
negative.code:   real(real64) :: log_alpha1
    real(real64) :: log_alpha2
    real(real64) :: amax
    real(real64) :: log_fwa_amax
  
  contains
  
  