zig/std/math/expo2.zig
Andrew Kelley 3671582c15 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 04:10:11 -05:00

29 lines
685 B
Zig

const math = @import("index.zig");
pub fn expo2(x: var) @typeOf(x) {
const T = @typeOf(x);
return switch (T) {
f32 => expo2f(x),
f64 => expo2d(x),
else => @compileError("expo2 not implemented for " ++ @typeName(T)),
};
}
fn expo2f(x: f32) f32 {
const k: u32 = 235;
const kln2 = 0x1.45C778p+7;
const u = (0x7F + k / 2) << 23;
const scale = @bitCast(f32, u);
return math.exp(x - kln2) * scale * scale;
}
fn expo2d(x: f64) f64 {
const k: u32 = 2043;
const kln2 = 0x1.62066151ADD8BP+10;
const u = (0x3FF + k / 2) << 20;
const scale = @bitCast(f64, u64(u) << 32);
return math.exp(x - kln2) * scale * scale;
}