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LibJS: Add spec comments to MathObject::atan

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Shannon Booth 2023-05-28 23:32:33 +12:00 • committed by Andreas Kling
parent b7e31ba194
commit 979973ca0e
1 changed files with 59 additions and 14 deletions
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73
Userland/Libraries/LibJS/Runtime/MathObject.cpp
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@ -2,6 +2,7 @@
* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2020-2023, Linus Groh <linusg@serenityos.org>
* Copyright (c) 2021, Idan Horowitz <idan.horowitz@serenityos.org>
* Copyright (c) 2023, Shannon Booth <shannon.ml.booth@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
@ -225,57 +226,101 @@ JS_DEFINE_NATIVE_FUNCTION(MathObject::atan2)
{
auto constexpr three_quarters_pi = M_PI_4 + M_PI_2;
// 1. Let ny be ? ToNumber(y).
auto y = TRY(vm.argument(0).to_number(vm));
// 2. Let nx be ? ToNumber(x).
auto x = TRY(vm.argument(1).to_number(vm));
// 3. If ny is NaN or nx is NaN, return NaN.
if (y.is_nan() || x.is_nan())
return js_nan();
// 4. If ny is +∞𝔽, then
if (y.is_positive_infinity()) {
// a. If nx is +∞𝔽, return an implementation-approximated Number value representing π / 4.
if (x.is_positive_infinity())
return Value(M_PI_4);
else if (x.is_negative_infinity())
// b. If nx is -∞𝔽, return an implementation-approximated Number value representing 3π / 4.
if (x.is_negative_infinity())
return Value(three_quarters_pi);
else
return Value(M_PI_2);
// c. Return an implementation-approximated Number value representing π / 2.
return Value(M_PI_2);
}
// 5. If ny is -∞𝔽, then
if (y.is_negative_infinity()) {
// a. If nx is +∞𝔽, return an implementation-approximated Number value representing -π / 4.
if (x.is_positive_infinity())
return Value(-M_PI_4);
else if (x.is_negative_infinity())
// b. If nx is -∞𝔽, return an implementation-approximated Number value representing -3π / 4.
if (x.is_negative_infinity())
return Value(-three_quarters_pi);
else
return Value(-M_PI_2);
// c. Return an implementation-approximated Number value representing -π / 2.
return Value(-M_PI_2);
}
// 6. If ny is +0𝔽, then
if (y.is_positive_zero()) {
// a. If nx > +0𝔽 or nx is +0𝔽, return +0𝔽.
if (x.as_double() > 0 || x.is_positive_zero())
return Value(0.0);
else
return Value(M_PI);
// b. Return an implementation-approximated Number value representing π.
return Value(M_PI);
}
// 7. If ny is -0𝔽, then
if (y.is_negative_zero()) {
// a. If nx > +0𝔽 or nx is +0𝔽, return -0𝔽
if (x.as_double() > 0 || x.is_positive_zero())
return Value(-0.0);
else
return Value(-M_PI);
// b. Return an implementation-approximated Number value representing -π.
return Value(-M_PI);
}
// 8. Assert: ny is finite and is neither +0𝔽 nor -0𝔽.
VERIFY(y.is_finite_number() && !y.is_positive_zero() && !y.is_negative_zero());
// 9. If ny > +0𝔽, then
if (y.as_double() > 0) {
// a. If nx is +∞𝔽, return +0𝔽.
if (x.is_positive_infinity())
return Value(0);
else if (x.is_negative_infinity())
// b. If nx is -∞𝔽, return an implementation-approximated Number value representing π.
if (x.is_negative_infinity())
return Value(M_PI);
else if (x.is_positive_zero() || x.is_negative_zero())
// c. If nx is either +0𝔽 or -0𝔽, return an implementation-approximated Number value representing π / 2.
if (x.is_positive_zero() || x.is_negative_zero())
return Value(M_PI_2);
}
// 10. If ny < -0𝔽, then
if (y.as_double() < 0) {
// a. If nx is +∞𝔽, return -0𝔽.
if (x.is_positive_infinity())
return Value(-0.0);
else if (x.is_negative_infinity())
// b. If nx is -∞𝔽, return an implementation-approximated Number value representing -π.
if (x.is_negative_infinity())
return Value(-M_PI);
else if (x.is_positive_zero() || x.is_negative_zero())
// c. If nx is either +0𝔽 or -0𝔽, return an implementation-approximated Number value representing -π / 2.
if (x.is_positive_zero() || x.is_negative_zero())
return Value(-M_PI_2);
}
// 11. Assert: nx is finite and is neither +0𝔽 nor -0𝔽.
VERIFY(x.is_finite_number() && !x.is_positive_zero() && !x.is_negative_zero());
// 12. Return an implementation-approximated Number value representing the result of the inverse tangent of the quotient ℝ(ny) / ℝ(nx).
return Value(::atan2(y.as_double(), x.as_double()));
}