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std.math.complex: fix acosh/atan/cosh/sqrt

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Some of these are upstream changes since the original port, others are
translation errors.
This commit is contained in:
Marc Tiehuis 2024-07-29 16:26:09 +12:00
parent f219286573
commit 2bd7af63d7
4 changed files with 14 additions and 40 deletions
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6
lib/std/math/complex/acosh.zig
View File

@ -8,7 +8,11 @@ const Complex = cmath.Complex;
pub fn acosh(z: anytype) Complex(@TypeOf(z.re, z.im)) {
const T = @TypeOf(z.re, z.im);
const q = cmath.acos(z);
return Complex(T).init(-q.im, q.re);
return if (math.signbit(z.im))
Complex(T).init(q.im, -q.re)
else
Complex(T).init(-q.im, q.re);
}
const epsilon = 0.0001;

38
lib/std/math/complex/atan.zig
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@ -32,37 +32,22 @@ fn redupif32(x: f32) f32 {
t -= 0.5;
}
const u = @as(f32, @floatFromInt(@as(i32, @intFromFloat(t))));
return ((x - u * DP1) - u * DP2) - t * DP3;
const u: f32 = @trunc(t);
return ((x - u * DP1) - u * DP2) - u * DP3;
}
fn atan32(z: Complex(f32)) Complex(f32) {
const maxnum = 1.0e38;
const x = z.re;
const y = z.im;
if ((x == 0.0) and (y > 1.0)) {
// overflow
return Complex(f32).init(maxnum, maxnum);
}
const x2 = x * x;
var a = 1.0 - x2 - (y * y);
if (a == 0.0) {
// overflow
return Complex(f32).init(maxnum, maxnum);
}
var t = 0.5 * math.atan2(2.0 * x, a);
const w = redupif32(t);
t = y - 1.0;
a = x2 + t * t;
if (a == 0.0) {
// overflow
return Complex(f32).init(maxnum, maxnum);
}
t = y + 1.0;
a = (x2 + (t * t)) / a;
@ -81,37 +66,22 @@ fn redupif64(x: f64) f64 {
t -= 0.5;
}
const u = @as(f64, @floatFromInt(@as(i64, @intFromFloat(t))));
return ((x - u * DP1) - u * DP2) - t * DP3;
const u: f64 = @trunc(t);
return ((x - u * DP1) - u * DP2) - u * DP3;
}
fn atan64(z: Complex(f64)) Complex(f64) {
const maxnum = 1.0e308;
const x = z.re;
const y = z.im;
if ((x == 0.0) and (y > 1.0)) {
// overflow
return Complex(f64).init(maxnum, maxnum);
}
const x2 = x * x;
var a = 1.0 - x2 - (y * y);
if (a == 0.0) {
// overflow
return Complex(f64).init(maxnum, maxnum);
}
var t = 0.5 * math.atan2(2.0 * x, a);
const w = redupif64(t);
t = y - 1.0;
a = x2 + t * t;
if (a == 0.0) {
// overflow
return Complex(f64).init(maxnum, maxnum);
}
t = y + 1.0;
a = (x2 + (t * t)) / a;

6
lib/std/math/complex/cosh.zig
View File

@ -34,7 +34,7 @@ fn cosh32(z: Complex(f32)) Complex(f32) {
if (ix < 0x7f800000 and iy < 0x7f800000) {
if (iy == 0) {
return Complex(f32).init(math.cosh(x), y);
return Complex(f32).init(math.cosh(x), x * y);
}
// small x: normal case
if (ix < 0x41100000) {
@ -45,7 +45,7 @@ fn cosh32(z: Complex(f32)) Complex(f32) {
if (ix < 0x42b17218) {
// x < 88.7: exp(|x|) won't overflow
const h = @exp(@abs(x)) * 0.5;
return Complex(f32).init(math.copysign(h, x) * @cos(y), h * @sin(y));
return Complex(f32).init(h * @cos(y), math.copysign(h, x) * @sin(y));
}
// x < 192.7: scale to avoid overflow
else if (ix < 0x4340b1e7) {
@ -68,7 +68,7 @@ fn cosh32(z: Complex(f32)) Complex(f32) {
if (hx & 0x7fffff == 0) {
return Complex(f32).init(x * x, math.copysign(@as(f32, 0.0), x) * y);
}
return Complex(f32).init(x, math.copysign(@as(f32, 0.0), (x + x) * y));
return Complex(f32).init(x * x, math.copysign(@as(f32, 0.0), (x + x) * y));
}
if (ix < 0x7f800000 and iy >= 0x7f800000) {

4
lib/std/math/complex/sqrt.zig
View File

@ -43,7 +43,7 @@ fn sqrt32(z: Complex(f32)) Complex(f32) {
// sqrt(-inf + i nan) = nan +- inf i
// sqrt(-inf + iy) = 0 + inf i
if (math.signbit(x)) {
return Complex(f32).init(@abs(x - y), math.copysign(x, y));
return Complex(f32).init(@abs(y - y), math.copysign(x, y));
} else {
return Complex(f32).init(x, math.copysign(y - y, y));
}
@ -94,7 +94,7 @@ fn sqrt64(z: Complex(f64)) Complex(f64) {
// sqrt(-inf + i nan) = nan +- inf i
// sqrt(-inf + iy) = 0 + inf i
if (math.signbit(x)) {
return Complex(f64).init(@abs(x - y), math.copysign(x, y));
return Complex(f64).init(@abs(y - y), math.copysign(x, y));
} else {
return Complex(f64).init(x, math.copysign(y - y, y));
}