Function delta_gates 

pub fn delta_gates(
    alpha: VReg,
    dt: VReg,
    a: VReg,
    beta: VReg,
    log_decay: VReg,
    decay: VReg,
    gate: VReg,
) -> Vec<Op>

Every value head’s decay and gate at once from the vectors v[alpha], v[dt], v[a], v[beta]: the decay exponents softplus(α + dt)·a into v[log_decay], the decays into v[decay], the gates σ(β) into v[gate].