From e72049bc61eedd2b7381b87b530428a83581cafe Mon Sep 17 00:00:00 2001 From: Linus Groh Date: Fri, 27 Oct 2023 14:50:39 +0100 Subject: [PATCH] std.math: Add isPositiveZero() and isNegativeZero() --- lib/std/json/dynamic_test.zig | 2 +- lib/std/math.zig | 2 ++ lib/std/math/asin.zig | 8 +++---- lib/std/math/asinh.zig | 8 +++---- lib/std/math/atan.zig | 8 +++---- lib/std/math/cbrt.zig | 10 ++++----- lib/std/math/expm1.zig | 4 ++-- lib/std/math/iszero.zig | 41 +++++++++++++++++++++++++++++++++++ lib/std/math/log1p.zig | 8 +++---- lib/std/math/sinh.zig | 8 +++---- lib/std/math/tanh.zig | 8 +++---- 11 files changed, 75 insertions(+), 32 deletions(-) create mode 100644 lib/std/math/iszero.zig diff --git a/lib/std/json/dynamic_test.zig b/lib/std/json/dynamic_test.zig index 23586066fd..326c00e9b6 100644 --- a/lib/std/json/dynamic_test.zig +++ b/lib/std/json/dynamic_test.zig @@ -347,7 +347,7 @@ test "negative zero" { var parsed = try parseFromTokenSource(Value, testing.allocator, &reader, .{}); defer parsed.deinit(); - try testing.expect(parsed.value.float == 0 and std.math.signbit(parsed.value.float)); + try testing.expect(std.math.isNegativeZero(parsed.value.float)); } fn smallBufferJsonReader(allocator: Allocator, io_reader: anytype) JsonReader(16, @TypeOf(io_reader)) { diff --git a/lib/std/math.zig b/lib/std/math.zig index b18d5bc3ed..57471e2b03 100644 --- a/lib/std/math.zig +++ b/lib/std/math.zig @@ -222,6 +222,8 @@ pub const isFinite = @import("math/isfinite.zig").isFinite; pub const isInf = @import("math/isinf.zig").isInf; pub const isPositiveInf = @import("math/isinf.zig").isPositiveInf; pub const isNegativeInf = @import("math/isinf.zig").isNegativeInf; +pub const isPositiveZero = @import("math/iszero.zig").isPositiveZero; +pub const isNegativeZero = @import("math/iszero.zig").isNegativeZero; pub const isNormal = @import("math/isnormal.zig").isNormal; pub const nextAfter = @import("math/nextafter.zig").nextAfter; pub const signbit = @import("math/signbit.zig").signbit; diff --git a/lib/std/math/asin.zig b/lib/std/math/asin.zig index dedd4d7e72..da16f92c3c 100644 --- a/lib/std/math/asin.zig +++ b/lib/std/math/asin.zig @@ -169,15 +169,15 @@ test "math.asin64" { } test "math.asin32.special" { - try expect(asin32(0.0) == 0.0); - try expect(asin32(-0.0) == -0.0); + try expect(math.isPositiveZero(asin32(0.0))); + try expect(math.isNegativeZero(asin32(-0.0))); try expect(math.isNan(asin32(-2))); try expect(math.isNan(asin32(1.5))); } test "math.asin64.special" { - try expect(asin64(0.0) == 0.0); - try expect(asin64(-0.0) == -0.0); + try expect(math.isPositiveZero(asin64(0.0))); + try expect(math.isNegativeZero(asin64(-0.0))); try expect(math.isNan(asin64(-2))); try expect(math.isNan(asin64(1.5))); } diff --git a/lib/std/math/asinh.zig b/lib/std/math/asinh.zig index 8abcc055b0..deadcc2885 100644 --- a/lib/std/math/asinh.zig +++ b/lib/std/math/asinh.zig @@ -111,16 +111,16 @@ test "math.asinh64" { } test "math.asinh32.special" { - try expect(asinh32(0.0) == 0.0); - try expect(@as(u32, @bitCast(asinh32(-0.0))) == @as(u32, 0x80000000)); + try expect(math.isPositiveZero(asinh32(0.0))); + try expect(math.isNegativeZero(asinh32(-0.0))); try expect(math.isPositiveInf(asinh32(math.inf(f32)))); try expect(math.isNegativeInf(asinh32(-math.inf(f32)))); try expect(math.isNan(asinh32(math.nan(f32)))); } test "math.asinh64.special" { - try expect(asinh64(0.0) == 0.0); - try expect(@as(u64, @bitCast(asinh64(-0.0))) == @as(u64, 0x8000000000000000)); + try expect(math.isPositiveZero(asinh64(0.0))); + try expect(math.isNegativeZero(asinh64(-0.0))); try expect(math.isPositiveInf(asinh64(math.inf(f64)))); try expect(math.isNegativeInf(asinh64(-math.inf(f64)))); try expect(math.isNan(asinh64(math.nan(f64)))); diff --git a/lib/std/math/atan.zig b/lib/std/math/atan.zig index 2b57ceb074..bf85bdab7e 100644 --- a/lib/std/math/atan.zig +++ b/lib/std/math/atan.zig @@ -239,8 +239,8 @@ test "math.atan64" { test "math.atan32.special" { const epsilon = 0.000001; - try expect(atan32(0.0) == 0.0); - try expect(atan32(-0.0) == -0.0); + try expect(math.isPositiveZero(atan32(0.0))); + try expect(math.isNegativeZero(atan32(-0.0))); try expect(math.approxEqAbs(f32, atan32(math.inf(f32)), math.pi / 2.0, epsilon)); try expect(math.approxEqAbs(f32, atan32(-math.inf(f32)), -math.pi / 2.0, epsilon)); } @@ -248,8 +248,8 @@ test "math.atan32.special" { test "math.atan64.special" { const epsilon = 0.000001; - try expect(atan64(0.0) == 0.0); - try expect(atan64(-0.0) == -0.0); + try expect(math.isPositiveZero(atan64(0.0))); + try expect(math.isNegativeZero(atan64(-0.0))); try expect(math.approxEqAbs(f64, atan64(math.inf(f64)), math.pi / 2.0, epsilon)); try expect(math.approxEqAbs(f64, atan64(-math.inf(f64)), -math.pi / 2.0, epsilon)); } diff --git a/lib/std/math/cbrt.zig b/lib/std/math/cbrt.zig index d932f3149f..22745ee4d5 100644 --- a/lib/std/math/cbrt.zig +++ b/lib/std/math/cbrt.zig @@ -127,7 +127,7 @@ test "math.cbrt" { test "math.cbrt32" { const epsilon = 0.000001; - try expect(cbrt32(0.0) == 0.0); + try expect(math.isPositiveZero(cbrt32(0.0))); try expect(math.approxEqAbs(f32, cbrt32(0.2), 0.584804, epsilon)); try expect(math.approxEqAbs(f32, cbrt32(0.8923), 0.962728, epsilon)); try expect(math.approxEqAbs(f32, cbrt32(1.5), 1.144714, epsilon)); @@ -138,7 +138,7 @@ test "math.cbrt32" { test "math.cbrt64" { const epsilon = 0.000001; - try expect(cbrt64(0.0) == 0.0); + try expect(math.isPositiveZero(cbrt64(0.0))); try expect(math.approxEqAbs(f64, cbrt64(0.2), 0.584804, epsilon)); try expect(math.approxEqAbs(f64, cbrt64(0.8923), 0.962728, epsilon)); try expect(math.approxEqAbs(f64, cbrt64(1.5), 1.144714, epsilon)); @@ -147,7 +147,7 @@ test "math.cbrt64" { } test "math.cbrt.special" { - try expect(cbrt32(0.0) == 0.0); + try expect(math.isPositiveZero(cbrt32(0.0))); try expect(@as(u32, @bitCast(cbrt32(-0.0))) == @as(u32, 0x80000000)); try expect(math.isPositiveInf(cbrt32(math.inf(f32)))); try expect(math.isNegativeInf(cbrt32(-math.inf(f32)))); @@ -155,8 +155,8 @@ test "math.cbrt.special" { } test "math.cbrt64.special" { - try expect(cbrt64(0.0) == 0.0); - try expect(@as(u64, @bitCast(cbrt64(-0.0))) == @as(u64, 0x8000000000000000)); + try expect(math.isPositiveZero(cbrt64(0.0))); + try expect(math.isNegativeZero(cbrt64(-0.0))); try expect(math.isPositiveInf(cbrt64(math.inf(f64)))); try expect(math.isNegativeInf(cbrt64(-math.inf(f64)))); try expect(math.isNan(cbrt64(math.nan(f64)))); diff --git a/lib/std/math/expm1.zig b/lib/std/math/expm1.zig index 8192573a88..fc47904101 100644 --- a/lib/std/math/expm1.zig +++ b/lib/std/math/expm1.zig @@ -293,7 +293,7 @@ test "math.exp1m" { test "math.expm1_32" { const epsilon = 0.000001; - try expect(expm1_32(0.0) == 0.0); + try expect(math.isPositiveZero(expm1_32(0.0))); try expect(math.approxEqAbs(f32, expm1_32(0.0), 0.0, epsilon)); try expect(math.approxEqAbs(f32, expm1_32(0.2), 0.221403, epsilon)); try expect(math.approxEqAbs(f32, expm1_32(0.8923), 1.440737, epsilon)); @@ -303,7 +303,7 @@ test "math.expm1_32" { test "math.expm1_64" { const epsilon = 0.000001; - try expect(expm1_64(0.0) == 0.0); + try expect(math.isPositiveZero(expm1_64(0.0))); try expect(math.approxEqAbs(f64, expm1_64(0.0), 0.0, epsilon)); try expect(math.approxEqAbs(f64, expm1_64(0.2), 0.221403, epsilon)); try expect(math.approxEqAbs(f64, expm1_64(0.8923), 1.440737, epsilon)); diff --git a/lib/std/math/iszero.zig b/lib/std/math/iszero.zig new file mode 100644 index 0000000000..2d288d01e8 --- /dev/null +++ b/lib/std/math/iszero.zig @@ -0,0 +1,41 @@ +const std = @import("../std.zig"); +const math = std.math; +const expect = std.testing.expect; + +/// Returns whether x is positive zero. +pub inline fn isPositiveZero(x: anytype) bool { + const T = @TypeOf(x); + const bit_count = @typeInfo(T).Float.bits; + const TBits = std.meta.Int(.unsigned, bit_count); + return @as(TBits, @bitCast(x)) == @as(TBits, 0); +} + +/// Returns whether x is negative zero. +pub inline fn isNegativeZero(x: anytype) bool { + const T = @TypeOf(x); + const bit_count = @typeInfo(T).Float.bits; + const TBits = std.meta.Int(.unsigned, bit_count); + return @as(TBits, @bitCast(x)) == @as(TBits, 1) << (bit_count - 1); +} + +test isPositiveZero { + inline for ([_]type{ f16, f32, f64, f80, f128 }) |T| { + try expect(isPositiveZero(@as(T, 0.0))); + try expect(!isPositiveZero(@as(T, -0.0))); + try expect(!isPositiveZero(math.floatMin(T))); + try expect(!isPositiveZero(math.floatMax(T))); + try expect(!isPositiveZero(math.inf(T))); + try expect(!isPositiveZero(-math.inf(T))); + } +} + +test isNegativeZero { + inline for ([_]type{ f16, f32, f64, f80, f128 }) |T| { + try expect(isNegativeZero(@as(T, -0.0))); + try expect(!isNegativeZero(@as(T, 0.0))); + try expect(!isNegativeZero(math.floatMin(T))); + try expect(!isNegativeZero(math.floatMax(T))); + try expect(!isNegativeZero(math.inf(T))); + try expect(!isNegativeZero(-math.inf(T))); + } +} diff --git a/lib/std/math/log1p.zig b/lib/std/math/log1p.zig index 1f986a20c8..4cfdcecec9 100644 --- a/lib/std/math/log1p.zig +++ b/lib/std/math/log1p.zig @@ -212,8 +212,8 @@ test "math.log1p_64" { test "math.log1p_32.special" { try expect(math.isPositiveInf(log1p_32(math.inf(f32)))); - try expect(log1p_32(0.0) == 0.0); - try expect(log1p_32(-0.0) == -0.0); + try expect(math.isPositiveZero(log1p_32(0.0))); + try expect(math.isNegativeZero(log1p_32(-0.0))); try expect(math.isNegativeInf(log1p_32(-1.0))); try expect(math.isNan(log1p_32(-2.0))); try expect(math.isNan(log1p_32(math.nan(f32)))); @@ -221,8 +221,8 @@ test "math.log1p_32.special" { test "math.log1p_64.special" { try expect(math.isPositiveInf(log1p_64(math.inf(f64)))); - try expect(log1p_64(0.0) == 0.0); - try expect(log1p_64(-0.0) == -0.0); + try expect(math.isPositiveZero(log1p_64(0.0))); + try expect(math.isNegativeZero(log1p_64(-0.0))); try expect(math.isNegativeInf(log1p_64(-1.0))); try expect(math.isNan(log1p_64(-2.0))); try expect(math.isNan(log1p_64(math.nan(f64)))); diff --git a/lib/std/math/sinh.zig b/lib/std/math/sinh.zig index 0082f61d3f..c3bd6e1b43 100644 --- a/lib/std/math/sinh.zig +++ b/lib/std/math/sinh.zig @@ -123,16 +123,16 @@ test "math.sinh64" { } test "math.sinh32.special" { - try expect(sinh32(0.0) == 0.0); - try expect(sinh32(-0.0) == -0.0); + try expect(math.isPositiveZero(sinh32(0.0))); + try expect(math.isNegativeZero(sinh32(-0.0))); try expect(math.isPositiveInf(sinh32(math.inf(f32)))); try expect(math.isNegativeInf(sinh32(-math.inf(f32)))); try expect(math.isNan(sinh32(math.nan(f32)))); } test "math.sinh64.special" { - try expect(sinh64(0.0) == 0.0); - try expect(sinh64(-0.0) == -0.0); + try expect(math.isPositiveZero(sinh64(0.0))); + try expect(math.isNegativeZero(sinh64(-0.0))); try expect(math.isPositiveInf(sinh64(math.inf(f64)))); try expect(math.isNegativeInf(sinh64(-math.inf(f64)))); try expect(math.isNan(sinh64(math.nan(f64)))); diff --git a/lib/std/math/tanh.zig b/lib/std/math/tanh.zig index 9c9a3e6801..41b4bc5387 100644 --- a/lib/std/math/tanh.zig +++ b/lib/std/math/tanh.zig @@ -135,16 +135,16 @@ test "math.tanh64" { } test "math.tanh32.special" { - try expect(tanh32(0.0) == 0.0); - try expect(tanh32(-0.0) == -0.0); + try expect(math.isPositiveZero(tanh32(0.0))); + try expect(math.isNegativeZero(tanh32(-0.0))); try expect(tanh32(math.inf(f32)) == 1.0); try expect(tanh32(-math.inf(f32)) == -1.0); try expect(math.isNan(tanh32(math.nan(f32)))); } test "math.tanh64.special" { - try expect(tanh64(0.0) == 0.0); - try expect(tanh64(-0.0) == -0.0); + try expect(math.isPositiveZero(tanh64(0.0))); + try expect(math.isNegativeZero(tanh64(-0.0))); try expect(tanh64(math.inf(f64)) == 1.0); try expect(tanh64(-math.inf(f64)) == -1.0); try expect(math.isNan(tanh64(math.nan(f64))));