LemonBoy ff14451b4a std: Implement more useful approxEq semantics
Comparisons with absolute epsilons are usually useful when comparing
numbers to zero, for non-zero numbers it's advised to switch to relative
epsilons instead to obtain meaningful results (check [1] for more
details).

The new API introduces approxEqAbs and approxEqRel, where the former
aliases and deprecated the old `approxEq`, allowing the user to pick the
right tool for the job.

The documentation is meant to guide the user in the choice of the
correct alternative.

[1] https://randomascii.wordpress.com/2012/02/25/comparing-floating-point-numbers-2012-edition/
2020-11-05 16:08:49 +01:00

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Zig

// SPDX-License-Identifier: MIT
// Copyright (c) 2015-2020 Zig Contributors
// This file is part of [zig](https://ziglang.org/), which is MIT licensed.
// The MIT license requires this copyright notice to be included in all copies
// and substantial portions of the software.
const std = @import("../../std.zig");
const testing = std.testing;
const math = std.math;
const cmath = math.complex;
const Complex = cmath.Complex;
/// Returns the sine of z.
pub fn sin(z: anytype) Complex(@TypeOf(z.re)) {
const T = @TypeOf(z.re);
const p = Complex(T).new(-z.im, z.re);
const q = cmath.sinh(p);
return Complex(T).new(q.im, -q.re);
}
const epsilon = 0.0001;
test "complex.csin" {
const a = Complex(f32).new(5, 3);
const c = sin(a);
testing.expect(math.approxEqAbs(f32, c.re, -9.654126, epsilon));
testing.expect(math.approxEqAbs(f32, c.im, 2.841692, epsilon));
}