| author |  Andrew Kelley <andrew@ziglang.org> 2018-04-15 15:20:54-04:00 |
| committer | Andrew Kelley <andrew@ziglang.org> 2018-04-15 15:22:27-04:00 |
| log | 859b10d8bfcca3c4a30798b4522fd88ec6c66de6 |
| tree | a62caedfaf8bf24e5eac24cc3ef630f01b536941 |
| parent | a8d794215e5031d60c5bd761a2478f382972bde6 |
std.math.ln and std.math.exp use float strict mode
closes #9204 files changed, 68 insertions(+), 0 deletions(-)
test- behavior.zig
- cases
- bugs
std/math/exp.zig+5
| ... | ... | @@ -6,6 +6,7 @@ |
| 6 | 6 | const std = @import("../index.zig"); |
| 7 | 7 | const math = std.math; |
| 8 | 8 | const assert = std.debug.assert; |
| 9 | const builtin = @import("builtin"); | |
| 9 | 10 | |
| 10 | 11 | pub fn exp(x: var) @typeOf(x) { |
| 11 | 12 | const T = @typeOf(x); |
| ... | ... | @@ -17,6 +18,8 @@ pub fn exp(x: var) @typeOf(x) { |
| 17 | 18 | } |
| 18 | 19 | |
| 19 | 20 | fn exp32(x_: f32) f32 { |
| 21 | @setFloatMode(this, builtin.FloatMode.Strict); | |
| 22 | ||
| 20 | 23 | const half = []f32 { 0.5, -0.5 }; |
| 21 | 24 | const ln2hi = 6.9314575195e-1; |
| 22 | 25 | const ln2lo = 1.4286067653e-6; |
| ... | ... | @@ -94,6 +97,8 @@ fn exp32(x_: f32) f32 { |
| 94 | 97 | } |
| 95 | 98 | |
| 96 | 99 | fn exp64(x_: f64) f64 { |
| 100 | @setFloatMode(this, builtin.FloatMode.Strict); | |
| 101 | ||
| 97 | 102 | const half = []const f64 { 0.5, -0.5 }; |
| 98 | 103 | const ln2hi: f64 = 6.93147180369123816490e-01; |
| 99 | 104 | const ln2lo: f64 = 1.90821492927058770002e-10; |
std/math/ln.zig+2
| ... | ... | @@ -89,6 +89,8 @@ pub fn ln_32(x_: f32) f32 { |
| 89 | 89 | } |
| 90 | 90 | |
| 91 | 91 | pub fn ln_64(x_: f64) f64 { |
| 92 | @setFloatMode(this, @import("builtin").FloatMode.Strict); | |
| 93 | ||
| 92 | 94 | const ln2_hi: f64 = 6.93147180369123816490e-01; |
| 93 | 95 | const ln2_lo: f64 = 1.90821492927058770002e-10; |
| 94 | 96 | const Lg1: f64 = 6.666666666666735130e-01; |
test/behavior.zig+1
| ... | ... | @@ -12,6 +12,7 @@ comptime { |
| 12 | 12 | _ = @import("cases/bugs/655.zig"); |
| 13 | 13 | _ = @import("cases/bugs/656.zig"); |
| 14 | 14 | _ = @import("cases/bugs/828.zig"); |
| 15 | _ = @import("cases/bugs/920.zig"); | |
| 15 | 16 | _ = @import("cases/cast.zig"); |
| 16 | 17 | _ = @import("cases/const_slice_child.zig"); |
| 17 | 18 | _ = @import("cases/coroutines.zig"); |
test/cases/bugs/920.zig created+60
| ... | ... | @@ -0,0 +1,60 @@ |
| 1 | const std = @import("std"); | |
| 2 | const math = std.math; | |
| 3 | const Random = std.rand.Random; | |
| 4 | ||
| 5 | const ZigTable = struct { | |
| 6 | r: f64, | |
| 7 | x: [257]f64, | |
| 8 | f: [257]f64, | |
| 9 | ||
| 10 | pdf: fn(f64) f64, | |
| 11 | is_symmetric: bool, | |
| 12 | zero_case: fn(&Random, f64) f64, | |
| 13 | }; | |
| 14 | ||
| 15 | fn ZigTableGen(comptime is_symmetric: bool, comptime r: f64, comptime v: f64, comptime f: fn(f64) f64, | |
| 16 | comptime f_inv: fn(f64) f64, comptime zero_case: fn(&Random, f64) f64) ZigTable { | |
| 17 | var tables: ZigTable = undefined; | |
| 18 | ||
| 19 | tables.is_symmetric = is_symmetric; | |
| 20 | tables.r = r; | |
| 21 | tables.pdf = f; | |
| 22 | tables.zero_case = zero_case; | |
| 23 | ||
| 24 | tables.x[0] = v / f(r); | |
| 25 | tables.x[1] = r; | |
| 26 | ||
| 27 | for (tables.x[2..256]) |*entry, i| { | |
| 28 | const last = tables.x[2 + i - 1]; | |
| 29 | *entry = f_inv(v / last + f(last)); | |
| 30 | } | |
| 31 | tables.x[256] = 0; | |
| 32 | ||
| 33 | for (tables.f[0..]) |*entry, i| { | |
| 34 | *entry = f(tables.x[i]); | |
| 35 | } | |
| 36 | ||
| 37 | return tables; | |
| 38 | } | |
| 39 | ||
| 40 | const norm_r = 3.6541528853610088; | |
| 41 | const norm_v = 0.00492867323399; | |
| 42 | ||
| 43 | fn norm_f(x: f64) f64 { return math.exp(-x * x / 2.0); } | |
| 44 | fn norm_f_inv(y: f64) f64 { return math.sqrt(-2.0 * math.ln(y)); } | |
| 45 | fn norm_zero_case(random: &Random, u: f64) f64 { return 0.0; } | |
| 46 | ||
| 47 | const NormalDist = blk: { | |
| 48 | @setEvalBranchQuota(30000); | |
| 49 | break :blk ZigTableGen(true, norm_r, norm_v, norm_f, norm_f_inv, norm_zero_case); | |
| 50 | }; | |
| 51 | ||
| 52 | test "bug 920 fixed" { | |
| 53 | const NormalDist1 = blk: { | |
| 54 | break :blk ZigTableGen(true, norm_r, norm_v, norm_f, norm_f_inv, norm_zero_case); | |
| 55 | }; | |
| 56 | ||
| 57 | for (NormalDist1.f) |_, i| { | |
| 58 | std.debug.assert(NormalDist1.f[i] == NormalDist.f[i]); | |
| 59 | } | |
| 60 | } |