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41dd2beaac
* unify the logic for exporting math functions from compiler-rt,
with the appropriate suffixes and prefixes.
- add all missing f128 and f80 exports. Functions with missing
implementations call other functions and have TODO comments.
- also add f16 functions
* move math functions from freestanding libc to compiler-rt (#7265)
* enable all the f128 and f80 code in the stage2 compiler and behavior
tests (#11161).
* update std lib to use builtins rather than `std.math`.
35 lines
1.0 KiB
Zig
35 lines
1.0 KiB
Zig
const std = @import("../std.zig");
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const math = std.math;
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const testing = std.testing;
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/// Returns the natural logarithm of x.
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///
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/// Special Cases:
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/// - ln(+inf) = +inf
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/// - ln(0) = -inf
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/// - ln(x) = nan if x < 0
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/// - ln(nan) = nan
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/// TODO remove this in favor of `@log`.
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pub fn ln(x: anytype) @TypeOf(x) {
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const T = @TypeOf(x);
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switch (@typeInfo(T)) {
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.ComptimeFloat => {
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return @as(comptime_float, @log(x));
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},
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.Float => return @log(x),
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.ComptimeInt => {
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return @as(comptime_int, @floor(@log(@as(f64, x))));
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},
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.Int => |IntType| switch (IntType.signedness) {
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.signed => @compileError("ln not implemented for signed integers"),
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.unsigned => return @as(T, @floor(@log(@as(f64, x)))),
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},
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else => @compileError("ln not implemented for " ++ @typeName(T)),
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}
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}
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test "math.ln" {
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try testing.expect(ln(@as(f32, 0.2)) == @log(0.2));
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try testing.expect(ln(@as(f64, 0.2)) == @log(0.2));
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}
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