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Merged
merged 2 commits into from
Feb 23, 2024
Merged

Fix unexpected rounding signs on OPT26- #13365

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d6021e4
Update float tests to catch -0.0
sabiwara Feb 23, 2024
e7d3de0
Fix unexpected rounding signs on OPT26-
sabiwara Feb 23, 2024
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5 changes: 4 additions & 1 deletion .formatter.exs
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Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,10 @@
assert_same: 2,

# Errors tests
assert_eval_raise: 3
assert_eval_raise: 3,

# Float tests
float_assert: 1
],
normalize_bitstring_modifiers: false
]
11 changes: 8 additions & 3 deletions lib/elixir/lib/float.ex
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Original file line number Diff line number Diff line change
Expand Up @@ -374,8 +374,8 @@ defmodule Float do
case rounding do
:ceil when sign === 0 -> 1 / power_of_10(precision)
:floor when sign === 1 -> -1 / power_of_10(precision)
:ceil when sign === 1 -> -0.0
:half_up when sign === 1 -> -0.0
:ceil when sign === 1 -> minus_zero()
:half_up when sign === 1 -> minus_zero()
_ -> 0.0
end

Expand Down Expand Up @@ -406,7 +406,7 @@ defmodule Float do

cond do
num == 0 and sign == 1 ->
-0.0
minus_zero()

num == 0 ->
0.0
Expand All @@ -422,6 +422,11 @@ defmodule Float do
end
end

# TODO remove once we require Erlang/OTP 27+
# This function tricks the compiler to avoid this bug in previous versions:
# https://github.com/elixir-lang/elixir/blob/main/lib/elixir/lib/float.ex#L408-L412
defp minus_zero, do: -0.0

defp decompose(significant, initial) do
decompose(significant, 1, 0, initial)
end
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155 changes: 83 additions & 72 deletions lib/elixir/test/elixir/float_test.exs
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Expand Up @@ -5,6 +5,17 @@ defmodule FloatTest do

doctest Float

# TODO remove and replace by assert once we require Erlang/OTP 27+
# We can't easily distinguish between -0.0 and +0.0 on previous version
defmacrop float_assert({:===, _, [left, right]}) do
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I went with this approach because it gives us:

  • useful assertions
  • useful error messages on failure
  • can easily be removed since it is not here to stay

quote do
# note: these are pure functions so no need to use bind_quoted
# we favor a useful error message instead
assert unquote(left) === unquote(right)
assert to_string(unquote(left)) === to_string(unquote(right))
end
end

test "parse/1" do
assert Float.parse("12") === {12.0, ""}
assert Float.parse("-12") === {-12.0, ""}
Expand Down Expand Up @@ -45,153 +56,153 @@ defmodule FloatTest do
end

test "floor/1" do
assert Float.floor(12.524235) === 12.0
assert Float.floor(-12.5) === -13.0
assert Float.floor(-12.524235) === -13.0
assert Float.floor(7.5e3) === 7500.0
assert Float.floor(7.5432e3) === 7543.0
assert Float.floor(7.5e-3) === 0.0
assert Float.floor(-12.32453e4) === -123_246.0
assert Float.floor(-12.32453e-10) === -1.0
assert Float.floor(0.32453e-10) === 0.0
assert Float.floor(-0.32453e-10) === -1.0
assert Float.floor(1.32453e-10) === 0.0
float_assert Float.floor(12.524235) === 12.0
float_assert Float.floor(-12.5) === -13.0
float_assert Float.floor(-12.524235) === -13.0
float_assert Float.floor(7.5e3) === 7500.0
float_assert Float.floor(7.5432e3) === 7543.0
float_assert Float.floor(7.5e-3) === 0.0
float_assert Float.floor(-12.32453e4) === -123_246.0
float_assert Float.floor(-12.32453e-10) === -1.0
float_assert Float.floor(0.32453e-10) === 0.0
float_assert Float.floor(-0.32453e-10) === -1.0
float_assert Float.floor(1.32453e-10) === 0.0
end

describe "floor/2" do
test "with 0.0" do
for precision <- 0..15 do
assert Float.floor(0.0, precision) === 0.0
assert Float.floor(-0.0, precision) === -0.0
float_assert Float.floor(0.0, precision) === 0.0
float_assert Float.floor(-0.0, precision) === -0.0
end
end

test "floor/2 with precision" do
assert Float.floor(12.524235, 0) === 12.0
assert Float.floor(-12.524235, 0) === -13.0
float_assert Float.floor(12.524235, 0) === 12.0
float_assert Float.floor(-12.524235, 0) === -13.0

assert Float.floor(12.52, 2) === 12.51
assert Float.floor(-12.52, 2) === -12.52
float_assert Float.floor(12.52, 2) === 12.51
float_assert Float.floor(-12.52, 2) === -12.52

assert Float.floor(12.524235, 2) === 12.52
assert Float.floor(-12.524235, 3) === -12.525
float_assert Float.floor(12.524235, 2) === 12.52
float_assert Float.floor(-12.524235, 3) === -12.525

assert Float.floor(12.32453e-20, 2) === 0.0
assert Float.floor(-12.32453e-20, 2) === -0.01
float_assert Float.floor(12.32453e-20, 2) === 0.0
float_assert Float.floor(-12.32453e-20, 2) === -0.01

assert_raise ArgumentError, "precision 16 is out of valid range of 0..15", fn ->
Float.floor(1.1, 16)
end
end

test "with subnormal floats" do
assert Float.floor(-5.0e-324, 0) === -1.0
assert Float.floor(-5.0e-324, 1) === -0.1
assert Float.floor(-5.0e-324, 2) === -0.01
assert Float.floor(-5.0e-324, 15) === -0.000000000000001
float_assert Float.floor(-5.0e-324, 0) === -1.0
float_assert Float.floor(-5.0e-324, 1) === -0.1
float_assert Float.floor(-5.0e-324, 2) === -0.01
float_assert Float.floor(-5.0e-324, 15) === -0.000000000000001

for precision <- 0..15 do
assert Float.floor(5.0e-324, precision) === 0.0
float_assert Float.floor(5.0e-324, precision) === 0.0
end
end
end

test "ceil/1" do
assert Float.ceil(12.524235) === 13.0
assert Float.ceil(-12.5) === -12.0
assert Float.ceil(-12.524235) === -12.0
assert Float.ceil(7.5e3) === 7500.0
assert Float.ceil(7.5432e3) === 7544.0
assert Float.ceil(7.5e-3) === 1.0
assert Float.ceil(-12.32453e4) === -123_245.0
assert Float.ceil(-12.32453e-10) === -0.0
assert Float.ceil(0.32453e-10) === 1.0
assert Float.ceil(-0.32453e-10) === -0.0
assert Float.ceil(1.32453e-10) === 1.0
assert Float.ceil(0.0) === 0.0
float_assert Float.ceil(12.524235) === 13.0
float_assert Float.ceil(-12.5) === -12.0
float_assert Float.ceil(-12.524235) === -12.0
float_assert Float.ceil(7.5e3) === 7500.0
float_assert Float.ceil(7.5432e3) === 7544.0
float_assert Float.ceil(7.5e-3) === 1.0
float_assert Float.ceil(-12.32453e4) === -123_245.0
float_assert Float.ceil(-12.32453e-10) === -0.0
float_assert Float.ceil(0.32453e-10) === 1.0
float_assert Float.ceil(-0.32453e-10) === -0.0
float_assert Float.ceil(1.32453e-10) === 1.0
float_assert Float.ceil(0.0) === 0.0
end

describe "ceil/2" do
test "with 0.0" do
for precision <- 0..15 do
assert Float.ceil(0.0, precision) === 0.0
assert Float.ceil(-0.0, precision) === -0.0
float_assert Float.ceil(0.0, precision) === 0.0
float_assert Float.ceil(-0.0, precision) === -0.0
end
end

test "with regular floats" do
assert Float.ceil(12.524235, 0) === 13.0
assert Float.ceil(-12.524235, 0) === -12.0
float_assert Float.ceil(12.524235, 0) === 13.0
float_assert Float.ceil(-12.524235, 0) === -12.0

assert Float.ceil(12.52, 2) === 12.52
assert Float.ceil(-12.52, 2) === -12.51
float_assert Float.ceil(12.52, 2) === 12.52
float_assert Float.ceil(-12.52, 2) === -12.51

assert Float.ceil(12.524235, 2) === 12.53
assert Float.ceil(-12.524235, 3) === -12.524
float_assert Float.ceil(12.524235, 2) === 12.53
float_assert Float.ceil(-12.524235, 3) === -12.524

assert Float.ceil(12.32453e-20, 2) === 0.01
assert Float.ceil(-12.32453e-20, 2) === -0.0
float_assert Float.ceil(12.32453e-20, 2) === 0.01
float_assert Float.ceil(-12.32453e-20, 2) === -0.0

assert Float.ceil(0.0, 2) === 0.0
float_assert Float.ceil(0.0, 2) === 0.0

assert_raise ArgumentError, "precision 16 is out of valid range of 0..15", fn ->
Float.ceil(1.1, 16)
end
end

test "with small floats rounded up to -0.0" do
assert Float.ceil(-0.1, 0) === -0.0
assert Float.ceil(-0.01, 1) === -0.0
float_assert Float.ceil(-0.1, 0) === -0.0
float_assert Float.ceil(-0.01, 1) === -0.0
end

test "with subnormal floats" do
assert Float.ceil(5.0e-324, 0) === 1.0
assert Float.ceil(5.0e-324, 1) === 0.1
assert Float.ceil(5.0e-324, 2) === 0.01
assert Float.ceil(5.0e-324, 15) === 0.000000000000001
float_assert Float.ceil(5.0e-324, 0) === 1.0
float_assert Float.ceil(5.0e-324, 1) === 0.1
float_assert Float.ceil(5.0e-324, 2) === 0.01
float_assert Float.ceil(5.0e-324, 15) === 0.000000000000001

for precision <- 0..15 do
assert Float.ceil(-5.0e-324, precision) === -0.0
float_assert Float.ceil(-5.0e-324, precision) === -0.0
end
end
end

describe "round/2" do
test "with 0.0" do
for precision <- 0..15 do
assert Float.round(0.0, precision) === 0.0
assert Float.round(-0.0, precision) === -0.0
float_assert Float.round(0.0, precision) === 0.0
float_assert Float.round(-0.0, precision) === -0.0
end
end

test "with regular floats" do
assert Float.round(5.5675, 3) === 5.567
assert Float.round(-5.5674, 3) === -5.567
assert Float.round(5.5, 3) === 5.5
assert Float.round(5.5e-10, 10) === 5.0e-10
assert Float.round(5.5e-10, 8) === 0.0
assert Float.round(5.0, 0) === 5.0
float_assert Float.round(5.5675, 3) === 5.567
float_assert Float.round(-5.5674, 3) === -5.567
float_assert Float.round(5.5, 3) === 5.5
float_assert Float.round(5.5e-10, 10) === 5.0e-10
float_assert Float.round(5.5e-10, 8) === 0.0
float_assert Float.round(5.0, 0) === 5.0

assert_raise ArgumentError, "precision 16 is out of valid range of 0..15", fn ->
Float.round(1.1, 16)
end
end

test "with small floats rounded to +0.0 / -0.0" do
assert Float.round(0.01, 0) === 0.0
assert Float.round(0.01, 1) === 0.0
float_assert Float.round(0.01, 0) === 0.0
float_assert Float.round(0.01, 1) === 0.0

assert Float.round(-0.01, 0) === -0.0
assert Float.round(-0.01, 1) === -0.0
float_assert Float.round(-0.01, 0) === -0.0
float_assert Float.round(-0.01, 1) === -0.0

assert Float.round(-0.49999, 0) === -0.0
assert Float.round(-0.049999, 1) === -0.0
float_assert Float.round(-0.49999, 0) === -0.0
float_assert Float.round(-0.049999, 1) === -0.0
end

test "with subnormal floats" do
for precision <- 0..15 do
assert Float.round(5.0e-324, precision) === 0.0
assert Float.round(-5.0e-324, precision) === -0.0
float_assert Float.round(5.0e-324, precision) === 0.0
float_assert Float.round(-5.0e-324, precision) === -0.0
end
end
end
Expand Down