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float: fix negative-zero/zero almost_equal

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This commit is contained in:
Danny Robson 2015-01-29 15:44:57 +11:00
parent 794a688470
commit c841aadda0
2 changed files with 8 additions and 0 deletions
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6
float.cpp
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@ -126,6 +126,12 @@ ieee_float<E, S>::almost_equal (floating_t _a,
if (a.s == b.s) if (a.s == b.s)
return true; return true;
// Order as twos complement to avoid negative zero/zero comparison issues
if (a.s < 0)
a.s = (1L << (TOTAL_BITS - 1)) - a.s;
if (b.s < 0)
b.s = (1L << (TOTAL_BITS - 1)) - b.s;
uint_t diff = std::abs (a.s - b.s); uint_t diff = std::abs (a.s - b.s);
return diff <= ulps; return diff <= ulps;
} }

2
test/maths/maths.cpp
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@ -23,6 +23,8 @@ main (int, char **) {
CHECK (!almost_equal (numeric_limits<double>::quiet_NaN (), CHECK (!almost_equal (numeric_limits<double>::quiet_NaN (),
numeric_limits<double>::quiet_NaN ())); numeric_limits<double>::quiet_NaN ()));
CHECK (almost_equal (0.f, -0.f));
CHECK (almost_equal (0., -0.));
CHECK_EQ (min (-2, 0, 2), -2); CHECK_EQ (min (-2, 0, 2), -2);
CHECK_EQ (max (-2, 0, 2), 2); CHECK_EQ (max (-2, 0, 2), 2);