zig/std/math/isfinite.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

31 lines
820 B
Zig

const math = @import("index.zig");
const assert = @import("../debug.zig").assert;
pub fn isFinite(x: var) -> bool {
const T = @typeOf(x);
switch (T) {
f32 => {
const bits = @bitCast(u32, x);
bits & 0x7FFFFFFF < 0x7F800000
},
f64 => {
const bits = @bitCast(u64, x);
bits & (@maxValue(u64) >> 1) < (0x7FF << 52)
},
else => {
@compileError("isFinite not implemented for " ++ @typeName(T));
},
}
}
test "isFinite" {
assert(isFinite(f32(0.0)));
assert(isFinite(f32(-0.0)));
assert(isFinite(f64(0.0)));
assert(isFinite(f64(-0.0)));
assert(!isFinite(math.inf(f32)));
assert(!isFinite(-math.inf(f32)));
assert(!isFinite(math.inf(f64)));
assert(!isFinite(-math.inf(f64)));
}