Re: [Boost-users] [multiprecision] Empty intervals and intervalswithNaN check

Subject: Re: [Boost-users] [multiprecision] Empty intervals and intervalswithNaN check
From: Александров Петр (petr_aleksandrov_at_[hidden])
Date: 2013-11-21 16:35:27

21.11.2013 17:04, John Maddock пишет:
>> No, the class is a very thin wrapper around mpfi so there's 
>> practically no error checking.  I really should add some error checks 
>> to the functions that create new intervals (i.e. assignment operators 
>> from two "components"): I'll do that shortly.
>
> Here's the patch for better error checks going in Trunk, hopefully 
> that should stop most invalid intervals from ever occurring in the 
> first place:
>
> Index: mpfi.hpp
> ===================================================================
> --- mpfi.hpp (revision 86537)
> +++ mpfi.hpp (working copy)
> @@ -179,6 +179,8 @@
>    }
>    mpfi_float_imp& operator = (const char* s)
>    {
> +      using default_ops::eval_fpclassify;
> +
>       if(m_data[0].left._mpfr_d == 0)
>          mpfi_init2(m_data, 
> multiprecision::detail::digits10_2_2(digits10 ? digits10 : 
> get_default_precision()));
>
> @@ -203,7 +205,22 @@
>             part.erase();
>          b = part.c_str();
>
> -         mpfi_interv_fr(m_data, a.data(), b.data());
> +         if(eval_fpclassify(a) == FP_NAN)
> +         {
> +            mpfi_set_fr(this->data(), a.data());
> +         }
> +         else if(eval_fpclassify(b) == FP_NAN)
> +         {
> +            mpfi_set_fr(this->data(), b.data());
> +         }
> +         else
> +         {
> +            if(a.compare(b) > 0)
> +            {
> +               BOOST_THROW_EXCEPTION(std::runtime_error("Attempt to 
> create interval with invalid range (start is greater than end)."));
> +            }
> +            mpfi_interv_fr(m_data, a.data(), b.data());
> +         }
>       }
>       else if(mpfi_set_str(m_data, s, 10) != 0)
>       {
> @@ -745,7 +762,23 @@
> template <unsigned D1, unsigned D2, mpfr_allocation_type AllocationType>
> inline void assign_components(mpfi_float_backend<D1>& result, const 
> mpfr_float_backend<D2, AllocationType>& a, const 
> mpfr_float_backend<D2, AllocationType>& b)
> {
> -   mpfi_interv_fr(result.data(), a.data(), b.data());
> +   using default_ops::eval_fpclassify;
> +   if(eval_fpclassify(a) == FP_NAN)
> +   {
> +      mpfi_set_fr(result.data(), a.data());
> +   }
> +   else if(eval_fpclassify(b) == FP_NAN)
> +   {
> +      mpfi_set_fr(result.data(), b.data());
> +   }
> +   else
> +   {
> +      if(a.compare(b) > 0)
> +      {
> +         BOOST_THROW_EXCEPTION(std::runtime_error("Attempt to create 
> interval with invalid range (start is greater than end)."));
> +      }
> +      mpfi_interv_fr(result.data(), a.data(), b.data());
> +   }
> }
>
> template <unsigned Digits10, class V>
>
> John.
> _______________________________________________
> Boost-users mailing list
> Boost-users_at_[hidden]
> http://lists.boost.org/mailman/listinfo.cgi/boost-users
>
>
Probably it will be better to allow a user to select: check empty 
intervals and NaN (during creation and assignment too) or not.
Kind regards, Petr.