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zig/std/math/pow.zig

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Add math special case tests and general fixes - Should cover special case inputs for most functions - Fixed a number of runtime panicking behaviour reliant on shift overflow/division by zero etc.
2017-06-20 12:01:04 +01:00
// Special Cases:
//
// pow(x, +-0) = 1 for any x
// pow(1, y) = 1 for any y
// pow(x, 1) = x for any x
// pow(nan, y) = nan
// pow(x, nan) = nan
// pow(+-0, y) = +-inf for y an odd integer < 0
// pow(+-0, -inf) = +inf
// pow(+-0, +inf) = +0
// pow(+-0, y) = +inf for finite y < 0 and not an odd integer
// pow(+-0, y) = +-0 for y an odd integer > 0
// pow(+-0, y) = +0 for finite y > 0 and not an odd integer
// pow(-1, +-inf) = 1
// pow(x, +inf) = +inf for |x| > 1
// pow(x, -inf) = +0 for |x| > 1
// pow(x, +inf) = +0 for |x| < 1
// pow(x, -inf) = +inf for |x| < 1
// pow(+inf, y) = +inf for y > 0
// pow(+inf, y) = +0 for y < 0
// pow(-inf, y) = pow(-0, -y)
// pow(x, y) = nan for finite x < 0 and finite non-integer y
disable some of the failing tests See #537
2017-10-15 07:04:21 +01:00
const builtin = @import("builtin");
move std/debug.zig to a subdirectory self hosted compiler parser tests do some fuzz testing
2017-12-24 03:08:53 +00:00
const std = @import("../index.zig");
const math = std.math;
const assert = std.debug.assert;
Add math library This covers the majority of the functions as covered by the C99 specification for a math library. Code is adapted primarily from musl libc, with the pow and standard trigonometric functions adapted from the Go stdlib. Changes: - Remove assert expose in index and import as needed. - Add float log function and merge with existing base 2 integer implementation. See https://github.com/tiehuis/zig-fmath. See #374.
2017-06-16 09:26:10 +01:00
std: refactor pow to be generic
2017-06-18 01:39:45 +01:00
// This implementation is taken from the go stlib, musl is a bit more complex.
syntax: functions require return type. remove `->` 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.
2018-01-25 09:10:11 +00:00
pub fn pow(comptime T: type, x: T, y: T) T {
Get tests passing under release mode This does not fix the underlying issue in pow at this stage, but we may be able to narrow down the cause after adding tests for specific edge cases in functions.
2017-06-18 03:16:04 +01:00
@setFloatMode(this, @import("builtin").FloatMode.Strict);
std: refactor pow to be generic
2017-06-18 01:39:45 +01:00
if (T != f32 and T != f64) {
@compileError("pow not implemented for " ++ @typeName(T));
Add math library This covers the majority of the functions as covered by the C99 specification for a math library. Code is adapted primarily from musl libc, with the pow and standard trigonometric functions adapted from the Go stdlib. Changes: - Remove assert expose in index and import as needed. - Add float log function and merge with existing base 2 integer implementation. See https://github.com/tiehuis/zig-fmath. See #374.
2017-06-16 09:26:10 +01:00
}
// pow(x, +-0) = 1 for all x
// pow(1, y) = 1 for all y
if (y == 0 or x == 1) {
return 1;
}
// pow(nan, y) = nan for all y
// pow(x, nan) = nan for all x
if (math.isNan(x) or math.isNan(y)) {
std: refactor pow to be generic
2017-06-18 01:39:45 +01:00
return math.nan(T);
Add math library This covers the majority of the functions as covered by the C99 specification for a math library. Code is adapted primarily from musl libc, with the pow and standard trigonometric functions adapted from the Go stdlib. Changes: - Remove assert expose in index and import as needed. - Add float log function and merge with existing base 2 integer implementation. See https://github.com/tiehuis/zig-fmath. See #374.
2017-06-16 09:26:10 +01:00
}
// pow(x, 1) = x for all x
if (y == 1) {
return x;
}
// special case sqrt
if (y == 0.5) {
return math.sqrt(x);
}
if (y == -0.5) {
return 1 / math.sqrt(x);
}
if (x == 0) {
if (y < 0) {
// pow(+-0, y) = +- 0 for y an odd integer
if (isOddInteger(y)) {
std: refactor pow to be generic
2017-06-18 01:39:45 +01:00
return math.copysign(T, math.inf(T), x);
Add math library This covers the majority of the functions as covered by the C99 specification for a math library. Code is adapted primarily from musl libc, with the pow and standard trigonometric functions adapted from the Go stdlib. Changes: - Remove assert expose in index and import as needed. - Add float log function and merge with existing base 2 integer implementation. See https://github.com/tiehuis/zig-fmath. See #374.
2017-06-16 09:26:10 +01:00
}
// pow(+-0, y) = +inf for y an even integer
else {
std: refactor pow to be generic
2017-06-18 01:39:45 +01:00
return math.inf(T);
Add math library This covers the majority of the functions as covered by the C99 specification for a math library. Code is adapted primarily from musl libc, with the pow and standard trigonometric functions adapted from the Go stdlib. Changes: - Remove assert expose in index and import as needed. - Add float log function and merge with existing base 2 integer implementation. See https://github.com/tiehuis/zig-fmath. See #374.
2017-06-16 09:26:10 +01:00
}
} else {
if (isOddInteger(y)) {
return x;
} else {
return 0;
}
}
}
if (math.isInf(y)) {
Add math special case tests and general fixes - Should cover special case inputs for most functions - Fixed a number of runtime panicking behaviour reliant on shift overflow/division by zero etc.
2017-06-20 12:01:04 +01:00
// pow(-1, inf) = 1 for all x
Add math library This covers the majority of the functions as covered by the C99 specification for a math library. Code is adapted primarily from musl libc, with the pow and standard trigonometric functions adapted from the Go stdlib. Changes: - Remove assert expose in index and import as needed. - Add float log function and merge with existing base 2 integer implementation. See https://github.com/tiehuis/zig-fmath. See #374.
2017-06-16 09:26:10 +01:00
if (x == -1) {
Add math special case tests and general fixes - Should cover special case inputs for most functions - Fixed a number of runtime panicking behaviour reliant on shift overflow/division by zero etc.
2017-06-20 12:01:04 +01:00
return 1.0;
Add math library This covers the majority of the functions as covered by the C99 specification for a math library. Code is adapted primarily from musl libc, with the pow and standard trigonometric functions adapted from the Go stdlib. Changes: - Remove assert expose in index and import as needed. - Add float log function and merge with existing base 2 integer implementation. See https://github.com/tiehuis/zig-fmath. See #374.
2017-06-16 09:26:10 +01:00
}
// pow(x, +inf) = +0 for |x| < 1
// pow(x, -inf) = +0 for |x| > 1
else if ((math.fabs(x) < 1) == math.isPositiveInf(y)) {
return 0;
}
// pow(x, -inf) = +inf for |x| < 1
// pow(x, +inf) = +inf for |x| > 1
else {
std: refactor pow to be generic
2017-06-18 01:39:45 +01:00
return math.inf(T);
Add math library This covers the majority of the functions as covered by the C99 specification for a math library. Code is adapted primarily from musl libc, with the pow and standard trigonometric functions adapted from the Go stdlib. Changes: - Remove assert expose in index and import as needed. - Add float log function and merge with existing base 2 integer implementation. See https://github.com/tiehuis/zig-fmath. See #374.
2017-06-16 09:26:10 +01:00
}
}
if (math.isInf(x)) {
if (math.isNegativeInf(x)) {
std: refactor pow to be generic
2017-06-18 01:39:45 +01:00
return pow(T, 1 / x, -y);
Add math library This covers the majority of the functions as covered by the C99 specification for a math library. Code is adapted primarily from musl libc, with the pow and standard trigonometric functions adapted from the Go stdlib. Changes: - Remove assert expose in index and import as needed. - Add float log function and merge with existing base 2 integer implementation. See https://github.com/tiehuis/zig-fmath. See #374.
2017-06-16 09:26:10 +01:00
}
// pow(+inf, y) = +0 for y < 0
else if (y < 0) {
return 0;
}
// pow(+inf, y) = +0 for y > 0
else if (y > 0) {
std: refactor pow to be generic
2017-06-18 01:39:45 +01:00
return math.inf(T);
Add math library This covers the majority of the functions as covered by the C99 specification for a math library. Code is adapted primarily from musl libc, with the pow and standard trigonometric functions adapted from the Go stdlib. Changes: - Remove assert expose in index and import as needed. - Add float log function and merge with existing base 2 integer implementation. See https://github.com/tiehuis/zig-fmath. See #374.
2017-06-16 09:26:10 +01:00
}
}
var ay = y;
var flip = false;
if (ay < 0) {
ay = -ay;
flip = true;
}
const r1 = math.modf(ay);
var yi = r1.ipart;
var yf = r1.fpart;
if (yf != 0 and x < 0) {
std: refactor pow to be generic
2017-06-18 01:39:45 +01:00
return math.nan(T);
Add math library This covers the majority of the functions as covered by the C99 specification for a math library. Code is adapted primarily from musl libc, with the pow and standard trigonometric functions adapted from the Go stdlib. Changes: - Remove assert expose in index and import as needed. - Add float log function and merge with existing base 2 integer implementation. See https://github.com/tiehuis/zig-fmath. See #374.
2017-06-16 09:26:10 +01:00
}
std: refactor pow to be generic
2017-06-18 01:39:45 +01:00
if (yi >= 1 << (T.bit_count - 1)) {
Add math library This covers the majority of the functions as covered by the C99 specification for a math library. Code is adapted primarily from musl libc, with the pow and standard trigonometric functions adapted from the Go stdlib. Changes: - Remove assert expose in index and import as needed. - Add float log function and merge with existing base 2 integer implementation. See https://github.com/tiehuis/zig-fmath. See #374.
2017-06-16 09:26:10 +01:00
return math.exp(y * math.ln(x));
}
// a = a1 * 2^ae
std: refactor pow to be generic
2017-06-18 01:39:45 +01:00
var a1: T = 1.0;
Add math library This covers the majority of the functions as covered by the C99 specification for a math library. Code is adapted primarily from musl libc, with the pow and standard trigonometric functions adapted from the Go stdlib. Changes: - Remove assert expose in index and import as needed. - Add float log function and merge with existing base 2 integer implementation. See https://github.com/tiehuis/zig-fmath. See #374.
2017-06-16 09:26:10 +01:00
var ae: i32 = 0;
// a *= x^yf
if (yf != 0) {
if (yf > 0.5) {
yf -= 1;
yi += 1;
}
a1 = math.exp(yf * math.ln(x));
}
// a *= x^yi
const r2 = math.frexp(x);
var xe = r2.exponent;
var x1 = r2.significand;
var i = i32(yi);
while (i != 0) : (i >>= 1) {
if (i & 1 == 1) {
a1 *= x1;
ae += xe;
}
x1 *= x1;
xe <<= 1;
if (x1 < 0.5) {
x1 += x1;
xe -= 1;
}
}
// a *= a1 * 2^ae
if (flip) {
a1 = 1 / a1;
ae = -ae;
}
explicitly return from blocks instead of last statement being expression value closes #629
2017-12-22 05:50:30 +00:00
return math.scalbn(a1, ae);
Add math library This covers the majority of the functions as covered by the C99 specification for a math library. Code is adapted primarily from musl libc, with the pow and standard trigonometric functions adapted from the Go stdlib. Changes: - Remove assert expose in index and import as needed. - Add float log function and merge with existing base 2 integer implementation. See https://github.com/tiehuis/zig-fmath. See #374.
2017-06-16 09:26:10 +01:00
}
syntax: functions require return type. remove `->` 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.
2018-01-25 09:10:11 +00:00
fn isOddInteger(x: f64) bool {
std: refactor pow to be generic
2017-06-18 01:39:45 +01:00
const r = math.modf(x);
explicitly return from blocks instead of last statement being expression value closes #629
2017-12-22 05:50:30 +00:00
return r.fpart == 0.0 and i64(r.ipart) & 1 == 1;
Add math library This covers the majority of the functions as covered by the C99 specification for a math library. Code is adapted primarily from musl libc, with the pow and standard trigonometric functions adapted from the Go stdlib. Changes: - Remove assert expose in index and import as needed. - Add float log function and merge with existing base 2 integer implementation. See https://github.com/tiehuis/zig-fmath. See #374.
2017-06-16 09:26:10 +01:00
}
std: refactor pow to be generic
2017-06-18 01:39:45 +01:00
test "math.pow" {
Add math library This covers the majority of the functions as covered by the C99 specification for a math library. Code is adapted primarily from musl libc, with the pow and standard trigonometric functions adapted from the Go stdlib. Changes: - Remove assert expose in index and import as needed. - Add float log function and merge with existing base 2 integer implementation. See https://github.com/tiehuis/zig-fmath. See #374.
2017-06-16 09:26:10 +01:00
const epsilon = 0.000001;
Add math special case tests and general fixes - Should cover special case inputs for most functions - Fixed a number of runtime panicking behaviour reliant on shift overflow/division by zero etc.
2017-06-20 12:01:04 +01:00
assert(math.approxEq(f32, pow(f32, 0.0, 3.3), 0.0, epsilon));
std: refactor pow to be generic
2017-06-18 01:39:45 +01:00
assert(math.approxEq(f32, pow(f32, 0.8923, 3.3), 0.686572, epsilon));
assert(math.approxEq(f32, pow(f32, 0.2, 3.3), 0.004936, epsilon));
assert(math.approxEq(f32, pow(f32, 1.5, 3.3), 3.811546, epsilon));
assert(math.approxEq(f32, pow(f32, 37.45, 3.3), 155736.703125, epsilon));
workaround for llvm bug See #393 for details
2017-06-19 19:36:33 +01:00
assert(math.approxEq(f32, pow(f32, 89.123, 3.3), 2722489.5, epsilon));
Add math library This covers the majority of the functions as covered by the C99 specification for a math library. Code is adapted primarily from musl libc, with the pow and standard trigonometric functions adapted from the Go stdlib. Changes: - Remove assert expose in index and import as needed. - Add float log function and merge with existing base 2 integer implementation. See https://github.com/tiehuis/zig-fmath. See #374.
2017-06-16 09:26:10 +01:00
Add math special case tests and general fixes - Should cover special case inputs for most functions - Fixed a number of runtime panicking behaviour reliant on shift overflow/division by zero etc.
2017-06-20 12:01:04 +01:00
assert(math.approxEq(f64, pow(f64, 0.0, 3.3), 0.0, epsilon));
std: refactor pow to be generic
2017-06-18 01:39:45 +01:00
assert(math.approxEq(f64, pow(f64, 0.8923, 3.3), 0.686572, epsilon));
assert(math.approxEq(f64, pow(f64, 0.2, 3.3), 0.004936, epsilon));
assert(math.approxEq(f64, pow(f64, 1.5, 3.3), 3.811546, epsilon));
assert(math.approxEq(f64, pow(f64, 37.45, 3.3), 155736.7160616, epsilon));
assert(math.approxEq(f64, pow(f64, 89.123, 3.3), 2722490.231436, epsilon));
Add math library This covers the majority of the functions as covered by the C99 specification for a math library. Code is adapted primarily from musl libc, with the pow and standard trigonometric functions adapted from the Go stdlib. Changes: - Remove assert expose in index and import as needed. - Add float log function and merge with existing base 2 integer implementation. See https://github.com/tiehuis/zig-fmath. See #374.
2017-06-16 09:26:10 +01:00
}
Add math special case tests and general fixes - Should cover special case inputs for most functions - Fixed a number of runtime panicking behaviour reliant on shift overflow/division by zero etc.
2017-06-20 12:01:04 +01:00
test "math.pow.special" {
const epsilon = 0.000001;
assert(pow(f32, 4, 0.0) == 1.0);
assert(pow(f32, 7, -0.0) == 1.0);
assert(pow(f32, 45, 1.0) == 45);
assert(pow(f32, -45, 1.0) == -45);
assert(math.isNan(pow(f32, math.nan(f32), 5.0)));
assert(math.isNan(pow(f32, 5.0, math.nan(f32))));
assert(math.isPositiveInf(pow(f32, 0.0, -1.0)));
depend on embedded SoftFloat-3d instead of __float128 See #302 See #467
2017-09-14 06:44:22 +01:00
//assert(math.isNegativeInf(pow(f32, -0.0, -3.0))); TODO is this required?
Add math special case tests and general fixes - Should cover special case inputs for most functions - Fixed a number of runtime panicking behaviour reliant on shift overflow/division by zero etc.
2017-06-20 12:01:04 +01:00
assert(math.isPositiveInf(pow(f32, 0.0, -math.inf(f32))));
assert(math.isPositiveInf(pow(f32, -0.0, -math.inf(f32))));
assert(pow(f32, 0.0, math.inf(f32)) == 0.0);
assert(pow(f32, -0.0, math.inf(f32)) == 0.0);
assert(math.isPositiveInf(pow(f32, 0.0, -2.0)));
assert(math.isPositiveInf(pow(f32, -0.0, -2.0)));
assert(pow(f32, 0.0, 1.0) == 0.0);
assert(pow(f32, -0.0, 1.0) == -0.0);
assert(pow(f32, 0.0, 2.0) == 0.0);
assert(pow(f32, -0.0, 2.0) == 0.0);
assert(math.approxEq(f32, pow(f32, -1.0, math.inf(f32)), 1.0, epsilon));
assert(math.approxEq(f32, pow(f32, -1.0, -math.inf(f32)), 1.0, epsilon));
assert(math.isPositiveInf(pow(f32, 1.2, math.inf(f32))));
assert(math.isPositiveInf(pow(f32, -1.2, math.inf(f32))));
assert(pow(f32, 1.2, -math.inf(f32)) == 0.0);
assert(pow(f32, -1.2, -math.inf(f32)) == 0.0);
assert(pow(f32, 0.2, math.inf(f32)) == 0.0);
assert(pow(f32, -0.2, math.inf(f32)) == 0.0);
assert(math.isPositiveInf(pow(f32, 0.2, -math.inf(f32))));
assert(math.isPositiveInf(pow(f32, -0.2, -math.inf(f32))));
assert(math.isPositiveInf(pow(f32, math.inf(f32), 1.0)));
assert(pow(f32, math.inf(f32), -1.0) == 0.0);
depend on embedded SoftFloat-3d instead of __float128 See #302 See #467
2017-09-14 06:44:22 +01:00
//assert(pow(f32, -math.inf(f32), 5.0) == pow(f32, -0.0, -5.0)); TODO support negative 0?
Add math special case tests and general fixes - Should cover special case inputs for most functions - Fixed a number of runtime panicking behaviour reliant on shift overflow/division by zero etc.
2017-06-20 12:01:04 +01:00
assert(pow(f32, -math.inf(f32), -5.2) == pow(f32, -0.0, 5.2));
assert(math.isNan(pow(f32, -1.0, 1.2)));
assert(math.isNan(pow(f32, -12.4, 78.5)));
}
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