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Return undefined in frexp instead of 0 on nan input

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This is more in line what usual C implementations do.
This commit is contained in:
Marc Tiehuis 2017-06-22 19:29:57 +12:00
parent 5aff641f4b
commit e81bf1c38c
1 changed files with 19 additions and 6 deletions
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25
std/math/frexp.zig
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@ -2,7 +2,7 @@
//
// - frexp(+-0) = +-0, 0
// - frexp(+-inf) = +-inf, 0
// - frexp(nan) = nan, 0
// - frexp(nan) = nan, undefined
const math = @import("index.zig");
const assert = @import("../debug.zig").assert;
@ -46,9 +46,15 @@ fn frexp32(x: f32) -> frexp32_result {
}
return result;
} else if (e == 0xFF) {
// frexp(nan) = (nan, 0)
// frexp(nan) = (nan, undefined)
result.significand = x;
result.exponent = 0;
result.exponent = undefined;
// frexp(+-inf) = (+-inf, 0)
if (math.isInf(x)) {
result.exponent = 0;
}
return result;
}
@ -77,8 +83,15 @@ fn frexp64(x: f64) -> frexp64_result {
}
return result;
} else if (e == 0x7FF) {
// frexp(nan) = (nan, undefined)
result.significand = x;
result.exponent = 0;
result.exponent = undefined;
// frexp(+-inf) = (+-inf, 0)
if (math.isInf(x)) {
result.exponent = 0;
}
return result;
}
@ -137,7 +150,7 @@ test "math.frexp32.special" {
assert(math.isNegativeInf(r.significand) and r.exponent == 0);
r = frexp32(math.nan(f32));
assert(math.isNan(r.significand) and r.exponent == 0);
assert(math.isNan(r.significand));
}
test "math.frexp64.special" {
@ -156,5 +169,5 @@ test "math.frexp64.special" {
assert(math.isNegativeInf(r.significand) and r.exponent == 0);
r = frexp64(math.nan(f64));
assert(math.isNan(r.significand) and r.exponent == 0);
assert(math.isNan(r.significand));
}