zig/std/math/signbit.zig
Marc Tiehuis 4c16f9a3c3 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 20:32:31 +12:00

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Zig

const math = @import("index.zig");
const assert = @import("../debug.zig").assert;
pub fn signbit(x: var) -> bool {
const T = @typeOf(x);
switch (T) {
f32 => @inlineCall(signbit32, x),
f64 => @inlineCall(signbit64, x),
else => @compileError("signbit not implemented for " ++ @typeName(T)),
}
}
fn signbit32(x: f32) -> bool {
const bits = @bitCast(u32, x);
bits >> 31 != 0
}
fn signbit64(x: f64) -> bool {
const bits = @bitCast(u64, x);
bits >> 63 != 0
}
test "signbit" {
assert(signbit(f32(4.0)) == signbit32(4.0));
assert(signbit(f64(4.0)) == signbit64(4.0));
}
test "signbit32" {
assert(!signbit32(4.0));
assert(signbit32(-3.0));
}
test "signbit64" {
assert(!signbit64(4.0));
assert(signbit64(-3.0));
}