3671582c15
The purpose of this is: * Only one way to do things * Changing a function with void return type to return a possible error becomes a 1 character change, subtly encouraging people to use errors. See #632 Here are some imperfect sed commands for performing this update: remove arrow: ``` sed -i 's/\(\bfn\b.*\)-> /\1/g' $(find . -name "*.zig") ``` add void: ``` sed -i 's/\(\bfn\b.*\))\s*{/\1) void {/g' $(find ../ -name "*.zig") ``` Some cleanup may be necessary, but this should do the bulk of the work.
89 lines
2.4 KiB
Zig
89 lines
2.4 KiB
Zig
// Special Cases:
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//
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// - acosh(x) = snan if x < 1
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// - acosh(nan) = nan
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const builtin = @import("builtin");
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const std = @import("../index.zig");
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const math = std.math;
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const assert = std.debug.assert;
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pub fn acosh(x: var) @typeOf(x) {
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const T = @typeOf(x);
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return switch (T) {
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f32 => acosh32(x),
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f64 => acosh64(x),
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else => @compileError("acosh not implemented for " ++ @typeName(T)),
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};
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}
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// acosh(x) = log(x + sqrt(x * x - 1))
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fn acosh32(x: f32) f32 {
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const u = @bitCast(u32, x);
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const i = u & 0x7FFFFFFF;
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// |x| < 2, invalid if x < 1 or nan
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if (i < 0x3F800000 + (1 << 23)) {
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return math.log1p(x - 1 + math.sqrt((x - 1) * (x - 1) + 2 * (x - 1)));
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}
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// |x| < 0x1p12
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else if (i < 0x3F800000 + (12 << 23)) {
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return math.ln(2 * x - 1 / (x + math.sqrt(x * x - 1)));
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}
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// |x| >= 0x1p12
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else {
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return math.ln(x) + 0.693147180559945309417232121458176568;
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}
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}
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fn acosh64(x: f64) f64 {
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const u = @bitCast(u64, x);
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const e = (u >> 52) & 0x7FF;
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// |x| < 2, invalid if x < 1 or nan
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if (e < 0x3FF + 1) {
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return math.log1p(x - 1 + math.sqrt((x - 1) * (x - 1) + 2 * (x - 1)));
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}
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// |x| < 0x1p26
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else if (e < 0x3FF + 26) {
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return math.ln(2 * x - 1 / (x + math.sqrt(x * x - 1)));
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}
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// |x| >= 0x1p26 or nan
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else {
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return math.ln(x) + 0.693147180559945309417232121458176568;
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}
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}
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test "math.acosh" {
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assert(acosh(f32(1.5)) == acosh32(1.5));
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assert(acosh(f64(1.5)) == acosh64(1.5));
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}
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test "math.acosh32" {
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const epsilon = 0.000001;
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assert(math.approxEq(f32, acosh32(1.5), 0.962424, epsilon));
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assert(math.approxEq(f32, acosh32(37.45), 4.315976, epsilon));
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assert(math.approxEq(f32, acosh32(89.123), 5.183133, epsilon));
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assert(math.approxEq(f32, acosh32(123123.234375), 12.414088, epsilon));
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}
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test "math.acosh64" {
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const epsilon = 0.000001;
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assert(math.approxEq(f64, acosh64(1.5), 0.962424, epsilon));
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assert(math.approxEq(f64, acosh64(37.45), 4.315976, epsilon));
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assert(math.approxEq(f64, acosh64(89.123), 5.183133, epsilon));
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assert(math.approxEq(f64, acosh64(123123.234375), 12.414088, epsilon));
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}
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test "math.acosh32.special" {
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assert(math.isNan(acosh32(math.nan(f32))));
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assert(math.isSignalNan(acosh32(0.5)));
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}
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test "math.acosh64.special" {
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assert(math.isNan(acosh64(math.nan(f64))));
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assert(math.isSignalNan(acosh64(0.5)));
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}
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