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| author | flywind <43030857+xflywind@users.noreply.github.com> | 2020-12-30 08:09:30 -0600 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2020-12-30 15:09:30 +0100 |
| commit | 515cd454207ed9066c08ac8ef42407ae5ba62bc8 (patch) | |
| tree | 198194fab86a5fa63eb707ba6df3803e9274022e /lib/pure | |
| parent | 73f778e441cd4229af4115f762bd597a8a20fb74 (diff) | |
| download | Nim-515cd454207ed9066c08ac8ef42407ae5ba62bc8.tar.gz | |
Add math.copySign (#16406)
* add math.copySign * fix + tests
Diffstat (limited to 'lib/pure')
| -rw-r--r-- | lib/pure/math.nim | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/lib/pure/math.nim b/lib/pure/math.nim index 5b19a8ec0..76052ec3b 100644 --- a/lib/pure/math.nim +++ b/lib/pure/math.nim @@ -62,6 +62,9 @@ when defined(c) or defined(cpp): proc c_isnan(x: float): bool {.importc: "isnan", header: "<math.h>".} # a generic like `x: SomeFloat` might work too if this is implemented via a C macro. + proc c_copysign(x, y: cfloat): cfloat {.importc: "copysignf", header: "<math.h>".} + proc c_copysign(x, y: cdouble): cdouble {.importc: "copysign", header: "<math.h>".} + func binom*(n, k: int): int = ## Computes the `binomial coefficient <https://en.wikipedia.org/wiki/Binomial_coefficient>`_. runnableExamples: @@ -153,6 +156,40 @@ func isNaN*(x: SomeFloat): bool {.inline, since: (1,5,1).} = when defined(js): fn() else: result = c_isnan(x) +func copySign*[T: SomeFloat](x, y: T): T {.inline, since: (1, 5, 1).} = + ## Returns a value with the magnitude of `x` and the sign of `y`; + ## this works even if x or y are NaN or zero, both of which can carry a sign. + runnableExamples: + doAssert copySign(1.0, -0.0) == -1.0 + doAssert copySign(0.0, -0.0) == -0.0 + doAssert copySign(-1.0, 0.0) == 1.0 + doAssert copySign(10.0, 0.0) == 10.0 + + doAssert copySign(Inf, -1.0) == -Inf + doAssert copySign(-Inf, 1.0) == Inf + doAssert copySign(-1.0, NaN) == 1.0 + doAssert copySign(10.0, NaN) == 10.0 + + doAssert copySign(NaN, 0.0).isNaN + doAssert copySign(NaN, -0.0).isNaN + + # fails in VM and JS backend + doAssert copySign(1.0, copySign(NaN, -1.0)) == -1.0 + + # TODO use signbit for examples + template impl() = + if y > 0.0 or (y == 0.0 and 1.0 / y > 0.0): + result = abs(x) + elif y <= 0.0: + result = -abs(x) + else: # must be NaN + result = abs(x) + + when defined(js): impl() + else: + when nimvm: impl() + else: result = c_copysign(x, y) + func classify*(x: float): FloatClass = ## Classifies a floating point value. ## @@ -1159,3 +1196,4 @@ func lcm*[T](x: openArray[T]): T {.since: (1, 1).} = while i < x.len: result = lcm(result, x[i]) inc(i) + |