Enum Activation 

pub enum Activation {
    Gelu,
    GeluApprox,
    Silu,
    Relu,
    Sigmoid,
    Tanh,
    Exp,
    Log,
    Sqrt,
    Rsqrt,
    Neg,
    Abs,
    Sin,
    Cos,
    Tan,
    Atan,
    Recip,
    Round,
    Floor,
    Ceil,
    Sign,
    Softplus,
    Elu,
    Erf,
    HardSwish,
    HardSigmoid,
    Mish,
    Softsign,
    LogSigmoid,
}

Unary element-wise activation functions.

Variants

Gelu

GeluApprox

Silu

Relu

Sigmoid

Tanh

Exp

Log

Sqrt

Rsqrt

Neg

Abs

Sin

sin(x). Backward: dx = upstream · cos(x).

Cos

cos(x). Backward: dx = -upstream · sin(x).

Tan

tan(x). Backward: dx = upstream · sec²(x) = upstream · (1 + tan²(x)).

Atan

atan(x). Backward: dx = upstream · (1 / (1 + x²)).

Recip

Reciprocal 1 / x.

Round

Round to nearest integer (half-to-even), in f32. Forward: x.round(). Backward: STE — treats as identity, so the gradient passes through unchanged. Useful as a primitive for composing custom quantization schemes (Mul-by-recip-scale → Round → Clamp → Mul-by-scale = a hand-rolled FakeQuantize that the elementwise-region pass can fuse into a single kernel).

Floor

floor(x). Backward: 0 (piecewise-constant).

Ceil

ceil(x). Backward: 0.

Sign

sign(x) = -1/0/+1 (sign of zero is 0). Backward: 0.

Softplus

softplus(x) = ln(1 + eˣ). Backward: dx = u·sigmoid(x).

Elu

ELU (α=1): x if x>0 else eˣ-1. Backward: u·(1 if x>0 else eˣ).

Erf

erf(x) (Gauss error function). Backward: dx = u·(2/√π)·e^(-x²).

HardSwish

HardSwish x·clamp(x+3,0,6)/6. Backward: 0/1/(2x+3)/6 piecewise.

HardSigmoid

HardSigmoid clamp(x/6+0.5,0,1). Backward: 1/6 on |x|<3 else 0.

Mish

Mish x·tanh(softplus(x)).

Softsign

Softsign x/(1+|x|). Backward: 1/(1+|x|)².

LogSigmoid

LogSigmoid log(σ(x)) = min(x,0) − ln(1+e^(−|x|)). Backward: σ(−x).

Implementations

impl Activation

pub fn region_fusable(self) -> bool

Activations that may be folded into a fused ElementwiseRegion / TransformRegion chain. The newer scalar activations (Floor/Ceil/Sign/Softplus/Elu) run only on the standalone kernel path for now — the per-backend fused-region kernels don’t yet carry their opcodes, and their default passthrough would silently mis-evaluate them. Keeping them unfused is correct; a fused kernel is a perf follow-up.

impl Activation

pub const ALL: [Activation; 29]

Every Activation variant, for exhaustive test/parity fan-out.

pub const fn opcode_relu_first(self) -> u32

“Relu-first” activation opcode: CUDA / wgpu / ROCm forward unary kernels, and every backend’s activation-backward kernel (activation_backward.{cu,comp,cl} + Metal). Relu=0 … Gelu=9 … Recip=17 … LogSigmoid=28.

pub const fn opcode_gelu_first(self) -> u32

“Gelu-first” activation opcode: Vulkan and oneAPI forward unary kernels (act_id). Gelu=0, GeluApprox=1, Silu=2, Relu=3 … LogSigmoid=28. Note Round=16, Recip=17 (swapped vs enum order).

Trait Implementations

impl Clone for Activation

fn clone(&self) -> Activation

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Activation

impl Debug for Activation

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Activation

fn deserialize<__D>( __deserializer: __D, ) -> Result<Activation, <__D as Deserializer<'de>>::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Eq for Activation

impl Hash for Activation

fn hash<__H>(&self, state: &mut __H)

where __H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for Activation

fn eq(&self, other: &Activation) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Serialize for Activation

fn serialize<__S>( &self, __serializer: __S, ) -> Result<<__S as Serializer>::Ok, <__S as Serializer>::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Activation