[Boost-users] constructing rationals from mpfr_floats [multiprecision]

Subject: [Boost-users] constructing rationals from mpfr_floats [multiprecision]
From: Dani Brake (danielthebrake_at_[hidden])
Date: 2017-08-15 22:55:27

Hi,

1)  I am getting signaling due to division by 0.  The following lines are
faulty:

    mpfr_float p("1.1");
    mpq_rational q(p);

signal: integer divide by zero;

whereas this succeeds:

    mpq_rational q(1.1);

any one seen this before?  i'm on compiler Apple LLVM version 8.0.0
(clang-800.0.38) ,with homebrew-provided boost 1.64, mpfr 3.1.5, gmp 6.1.2.

--
2)  I also expected to be able to construct rationals as
    mpq_rational q("1.1")
but it fails to parse using the built-in constructor.  i mean, i understand
why (1.1 isn't a rational), but given that i can construct a rational from
a double, i figured that i'd get something reasonable from "1.1", namely
11/10.
--
thanks!
dani brake
university of wisconsin eau claire
ps i am not disabling mixed double-multiprecision arithmetic in this
scenario, in case you have been reading my other questions this last week