Re: [boost] Fwd: [Boost-users] [test] floating point comparison

Subject: Re: [boost] Fwd: [Boost-users] [test] floating point comparison
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2013-10-31 13:11:06

AMDG

On 10/31/2013 06:18 AM, Matthijs Möhlmann wrote:
> I've the following test program:
> 
> #define BOOST_TEST_DYN_LINK
> #define BOOST_TEST_MAIN
> #define BOOST_TEST_MODULE Master test suite
> #include <boost/test/unit_test.hpp>
> 
> BOOST_AUTO_TEST_CASE(TestCase) {
> 
>     BOOST_REQUIRE_CLOSE_FRACTION(45.00f, 45.17f, 0.004f);
> }
> 
> When I compile it with the following line:
> g++ -o main.o -c -Werror -Wall -std=c++11 -fvisibility=hidden
> -fvisibility-inlines-hidden -DBOOST_SPIRIT_USE_PHOENIX_V3 -DUTEST -g
> main.cpp
> g++ -o main main.o -lboost_unit_test_framework
> 
> I get the following output:
> Running 1 test case...
> 
> *** No errors detected
> 
> If I lower the tolerance to 0.0004f then I'll get the following:
> Running 1 test case...
> main.cpp(8): fatal error in "TestCase": difference{0.00376352} between
> 45.00f{45} and 45.17f{45.1699982} exceeds 0.00039999999
> 
> *** 1 failure detected in test suite "Master test suite"
> 
> Why does it say that the difference is 0.00376352 and not 0.17....... ?
> 

I suppose the output is a bit misleading.
The difference printed (0.0037...) is
approximately 0.17/45.

In Christ,
Steven Watanabe