Maximal overshoot is the maximum excursion beyond a pre-defined threshold, characterized differently in epidemics, astrophysics, signal processing, and control theory.
In epidemic models, it measures the fraction of additional infections post-peak, while in other fields it defines bounds on trajectory, mixing extent, or signal regrowth.
Its cross-disciplinary application provides actionable insights into system limits, influencing public health strategies, stellar evolution models, numerical schemes, and engineering controls.
Maximal overshoot is a domain-specific extremal notion for the largest excursion beyond a distinguished level. In the cited arXiv literature, that level may be the post-peak susceptible fraction in an epidemic, the classical Schwarzschild boundary of a convective core, the envelope reconstructed between FFT samples, the physical bounds of a square wave under shock-capturing discretization, the reference trajectory of a feedback loop, or the slow-roll plateau reached after Coleman–De Luccia tunneling. The shared mathematical pattern is an optimization or bounding problem over trajectories, signals, or admissible models, but the state variable and physical interpretation of “overshoot” differ substantially across fields (Nguyen et al., 2023, Guenther et al., 2014, Wunder et al., 2016, Zhang et al., 2021, wenczel et al., 2011, Freiheit et al., 2020, Dutta et al., 2011, Zhang et al., 2022).
1. Cross-disciplinary usage and formal definitions
The term does not denote a single universal observable. Instead, each literature fixes a baseline and then studies either the exact maximum attainable excess, the minimum unavoidable excess, or the maximal admissible extension beyond a formal boundary.
Domain
Formal definition
Extremal statement
Epidemic dynamics
Overshoot=S(t∗)−S∞=R01−S∞
Overshoot∗≈0.2984 at R0∗≈2.151
Convective-core modeling
δov=βHP or Dov(r)=D0exp[−2∣r−rcz∣/(fovHP)]
Procyon: δov,max≃1.5HP; solar-like stars: fov(Herwig)≲6×10−3 for solar conditions
Bandlimited signals
C1(L)=∥f∥t1,L,∞≤1sup∥f∥∞
finite-sum upper bounds for C1(L) and Nyquist-filter peak-regrowth
Shock-capturing schemes
Overshoot(ϕ,ν)=xmaxuϵovershoot(x;ϕ,ν)
scheme-dependent worst-case Overshoot∗≈0.29840
Continuous-time and governed control
Overshoot∗≈0.29841 or Overshoot∗≈0.29842
exact lower bounds from pole/zero data; RG-DC can enforce zero overshoot or a prescribed Overshoot∗≈0.29843
Inflation after tunneling
Overshoot∗≈0.29844
for Overshoot∗≈0.29845, Overshoot∗≈0.29846; for Overshoot∗≈0.29847, overshooting is entirely absent
A plausible implication is that “maximal overshoot” is best understood as a family of extremal constructions rather than a single transferable metric. The conserved quantities, dual programs, sampling operators, and asymptotic states that enter the calculation are specific to each model class (Nguyen et al., 2023, Wunder et al., 2016, wenczel et al., 2011).
2. Epidemic overshoot in the Kermack–McKendrick SIR model
In the classical Kermack–McKendrick SIR framework, the population fractions satisfy
Overshoot∗≈0.29848
with Overshoot∗≈0.29849 and R0∗≈2.1510. If R0∗≈2.1511 denotes the time of peak prevalence, then
R0∗≈2.1512
The epidemic overshoot is the fraction of the population infected after the peak: R0∗≈2.1513
where R0∗≈2.1514 (Nguyen et al., 2023).
Using the final-size relation
R0∗≈2.1515
the overshoot becomes the one-variable function
R0∗≈2.1516
Its critical point satisfies
R0∗≈2.1517
with numerical solution
R0∗≈2.1518
Thus, in the unmitigated SIR model, nearly R0∗≈2.1519 of the population becomes infected after the peak, and the total attack rate at the maximizing point is δov=βHP0 (Nguyen et al., 2023).
The same paper extends the analysis to SIRδov=βHP1V models. For a fixed pre-outbreak vaccinated fraction δov=βHP2,
δov=βHP3
For risk-driven vaccination δov=βHP4,
δov=βHP5
with equality in the limit δov=βHP6. In every scenario considered, the bound δov=βHP7 remains intact (Nguyen et al., 2023).
The Manaus example gives the notion epidemiological content. An early effective reproduction number δov=βHP8 implies δov=βHP9. Seroprevalence data corrected for antibody waning indicate that approximately Dov(r)=D0exp[−2∣r−rcz∣/(fovHP)]0 of the city had already been infected at the peak and about Dov(r)=D0exp[−2∣r−rcz∣/(fovHP)]1 by the end of the wave, yielding an empirical overshoot of roughly Dov(r)=D0exp[−2∣r−rcz∣/(fovHP)]2. The stated interpretation is that simple SIR-model bounds can anticipate the post-peak burden of disease once a sound estimate of Dov(r)=D0exp[−2∣r−rcz∣/(fovHP)]3 becomes available (Nguyen et al., 2023).
3. Convective-core overshoot in stellar structure and asteroseismology
In stellar evolution, overshoot refers to mixing beyond the formally convective boundary. Guenther et al. quantify Procyon’s convective-core overshoot by
Dov(r)=D0exp[−2∣r−rcz∣/(fovHP)]4
where Dov(r)=D0exp[−2∣r−rcz∣/(fovHP)]5 is the local pressure scale height and Dov(r)=D0exp[−2∣r−rcz∣/(fovHP)]6 ranges from Dov(r)=D0exp[−2∣r−rcz∣/(fovHP)]7 to Dov(r)=D0exp[−2∣r−rcz∣/(fovHP)]8 in steps of Dov(r)=D0exp[−2∣r−rcz∣/(fovHP)]9. Two conventional prescriptions were examined. In the raOv models, chemical mixing is uniform over δov,max≃1.5HP0 while the temperature gradient remains radiative, δov,max≃1.5HP1. In the adOv models, the same region is forced to be adiabatic, δov,max≃1.5HP2, mimicking penetrative convection. The Kuhfuss nonlocal theory instead solves a time-dependent turbulent kinetic-energy equation,
δov,max≃1.5HP3
and sets the convective boundary by the radius at which the convective velocity vanishes (Guenther et al., 2014).
The observational constraint is Bayesian evidence from a frequency-fitting framework with residual model
δov,max≃1.5HP4
where δov,max≃1.5HP5 is Gaussian and the systematic offset is marginalized using a “δov,max≃1.5HP6-prior.” Across all model variants, the evidence rises sharply from δov,max≃1.5HP7 to δov,max≃1.5HP8, peaks in the range δov,max≃1.5HP9–fov(Herwig)≲6×10−30, and then gradually declines for fov(Herwig)≲6×10−31. In the raOv sequence the maximum evidence occurs near fov(Herwig)≲6×10−32; in the raOvD sequence it shifts slightly to fov(Herwig)≲6×10−33. Relative to fov(Herwig)≲6×10−34, evidence ratios exceed fov(Herwig)≲6×10−35, corresponding to posterior odds fov(Herwig)≲6×10−36 in favor of substantial core overshoot. The quoted maximal overshoot is therefore
The inferred core enlargement is substantial. Without overshoot,
fov(Herwig)≲6×10−38
With fov(Herwig)≲6×10−39 these become
C1(L)=∥f∥t1,L,∞≤1sup∥f∥∞0
At C1(L)=∥f∥t1,L,∞≤1sup∥f∥∞1,
C1(L)=∥f∥t1,L,∞≤1sup∥f∥∞2
Guenther et al. explicitly note that these overshoot fractions exceed the “modest” C1(L)=∥f∥t1,L,∞≤1sup∥f∥∞3–C1(L)=∥f∥t1,L,∞≤1sup∥f∥∞4 often inferred from star-cluster turn-off or eclipsing-binary analyses, and they suggest rotationally induced circulations, tidal mixing from Procyon’s white-dwarf progenitor companion, or shear-driven turbulence as possible effective sources of the larger mixed region. They also state that the Kuhfuss nonlocal model fails to reach as high an evidence as the radiative-gradient prescription, which points to a predominantly over-mixing rather than penetrative mechanism (Guenther et al., 2014).
A distinct stellar literature constrains overshoot from the absence of a present-day solar convective core. In the exponential-diffusion overshoot model,
C1(L)=∥f∥t1,L,∞≤1sup∥f∥∞5
or equivalently
C1(L)=∥f∥t1,L,∞≤1sup∥f∥∞6
Helioseismic inversions require C1(L)=∥f∥t1,L,∞≤1sup∥f∥∞7 and C1(L)=∥f∥t1,L,∞≤1sup∥f∥∞8 for C1(L)=∥f∥t1,L,∞≤1sup∥f∥∞9. In the classical step model, a convective core survives to the solar age if C1(L)0, so one requires
C1(L)1
for solar conditions. In the exponential-diffusion model with C1(L)2,
C1(L)3
and this helioseismic limit is stricter than the neutrino-flux constraint (Zhang et al., 2022).
For C1(L)4, the combined asteroseismic results including the Sun follow approximately
C1(L)5
so that
C1(L)6
The largest allowed value in the sample is C1(L)7 at C1(L)8. The same framework also predicts isotope-dependent effective overshoot lengths, for example
C1(L)9
showing that the exponential-diffusion model does not impose a single fixed overshoot length on all species (Zhang et al., 2022).
4. Maximal overshoot and peak regrowth in bandlimited and Nyquist-filtered signals
For Overshoot(ϕ,ν)=xmaxuϵovershoot(x;ϕ,ν)0, the critical samples are Overshoot(ϕ,ν)=xmaxuϵovershoot(x;ϕ,ν)1, and for oversampling factor Overshoot(ϕ,ν)=xmaxuϵovershoot(x;ϕ,ν)2 one defines Overshoot(ϕ,ν)=xmaxuϵovershoot(x;ϕ,ν)3. The sample norm is
Overshoot(ϕ,ν)=xmaxuϵovershoot(x;ϕ,ν)4
and the maximal overshoot constant is
Overshoot(ϕ,ν)=xmaxuϵovershoot(x;ϕ,ν)5
Equivalently,
Overshoot(ϕ,ν)=xmaxuϵovershoot(x;ϕ,ν)6
This formulation treats overshoot as peak regrowth between samples rather than a state-space excursion (Wunder et al., 2016).
The same paper embeds the problem in an aperiodic transmit-filter model,
Overshoot(ϕ,ν)=xmaxuϵovershoot(x;ϕ,ν)7
and also in the generalized sampling series
Overshoot(ϕ,ν)=xmaxuϵovershoot(x;ϕ,ν)8
A classical bound due to Litsyn gives
Overshoot(ϕ,ν)=xmaxuϵovershoot(x;ϕ,ν)9
and hence, when Overshoot∗≈0.298400,
Overshoot∗≈0.298401
The paper refines this with a finite-sum estimate for
Overshoot∗≈0.298402
namely
Overshoot∗≈0.298403
with Overshoot∗≈0.298404. Since Overshoot∗≈0.298405, this is also a direct upper bound on the maximal overshoot (Wunder et al., 2016).
The extension to Nyquist filters is significant because classical bounds require Overshoot∗≈0.298406, whereas a Nyquist-criterion filter at half-rate Overshoot∗≈0.298407 necessarily has Overshoot∗≈0.298408. The new estimate remains finite even when Overshoot∗≈0.298409, and the paper also proves
Overshoot∗≈0.298410
which links worst-case overshoot to the Overshoot∗≈0.298411 tails of the transmit filter. Comparative analysis in the paper states that the new sum-bound uniformly improves earlier bounds for small and moderate Overshoot∗≈0.298412; for example, for Overshoot∗≈0.298413 the improvement can be Overshoot∗≈0.298414–Overshoot∗≈0.298415 over the Overshoot∗≈0.298416 law, and for Overshoot∗≈0.298417 it approaches Overshoot∗≈0.298418 (Wunder et al., 2016).
5. Numerical overshoots of shock-capturing schemes
Zhang and Zhang define overshoot for one SSP-RK3 step applied to linear advection of the unit-amplitude square wave
Overshoot∗≈0.298419
If Overshoot∗≈0.298420 is the numerical solution after one time step and Overshoot∗≈0.298421 is the exact shifted solution, the pointwise error is Overshoot∗≈0.298422. Only the amplitude beyond the physical bounds Overshoot∗≈0.298423 is measured: Overshoot∗≈0.298424
and the scalar metric is
Overshoot∗≈0.298425
This is an exact one-step error metric rather than an asymptotic norm (Zhang et al., 2021).
The derivation uses the Fourier expansion of the square wave, a semi-discrete symbol Overshoot∗≈0.298426, and the SSP-RK3 stability function
Overshoot∗≈0.298427
For odd Fourier modes, the amplification factor is
Overshoot∗≈0.298428
so the pointwise error becomes
Overshoot∗≈0.298429
The overshoot is then extracted by the physical-bound test above and maximized over Overshoot∗≈0.298430 (Zhang et al., 2021).
Two empirical findings are emphasized. First, the overshoot amplitude varies non-monotonously with the CFL number Overshoot∗≈0.298431; there is not a simple “more CFL Overshoot∗≈0.298432 more overshoot” law, and several WENO-type schemes attain minimum overshoot around Overshoot∗≈0.298433. For 5th-order WENO-Z, the minimum over Overshoot∗≈0.298434 occurs at Overshoot∗≈0.298435 and is approximately Overshoot∗≈0.298436 of its value at Overshoot∗≈0.298437. Second, overshoot depends strongly on the reduced wavenumber Overshoot∗≈0.298438: there is a threshold Overshoot∗≈0.298439 below which all schemes produce essentially zero overshoot, while for Overshoot∗≈0.298440 the overshoot grows, often in a staircase fashion, and some schemes exhibit local maxima and minima in Overshoot∗≈0.298441 (Zhang et al., 2021).
The worst-case survey over Overshoot∗≈0.298442 and Overshoot∗≈0.298443 gives the following approximate maxima:
The paper attributes these rankings to strict non-oscillatory behavior for TVD(minmod) and ENO3, Gibbs-type over/undershoots when higher-order ENO/WENO stencils span discontinuities, and reduced dissipation but larger linear-stencil oscillations in WENO-Z. The monotonicity-preserving post-limiter in MPWENO greatly curtails these oscillations (Zhang et al., 2021).
6. Overshoot in continuous-time control theory and reference governance
In continuous-time feedback systems, Wenczel and Hill formulate minimum achievable overshoot as a Banach-space optimization. For a plant
Overshoot∗≈0.298455
with unstable poles Overshoot∗≈0.298456 and nonminimum-phase zeros Overshoot∗≈0.298457, the attainable rational error signals form
Overshoot∗≈0.298458
The overshoot functional is
Overshoot∗≈0.298459
and the primal problem is
Overshoot∗≈0.298460
Fenchel duality yields the OS-dual
Overshoot∗≈0.298461
or, in density form,
Overshoot∗≈0.298462
The paper states strong duality: the minimum overshoot equals the maximum dual value (wenczel et al., 2011).
The key pole/zero sensitivity theorem isolates the dominant right-half-plane locations. If there is a nonminimum-phase zero Overshoot∗≈0.298463 and an unstable pole Overshoot∗≈0.298464 with Overshoot∗≈0.298465, then for a unit step
Overshoot∗≈0.298466
If there are no unstable poles but a single RHP zero Overshoot∗≈0.298467, then
Overshoot∗≈0.298468
For the illustrative plant
Overshoot∗≈0.298469
the bound is Overshoot∗≈0.298470, and the paper reports that time-domain simulation with a high-bandwidth rational stabilizing controller produces overshoot no smaller than about Overshoot∗≈0.298471, confirming that the bound Overshoot∗≈0.298472 is tight (wenczel et al., 2011).
A different control literature addresses overshoot mitigation rather than fundamental impossibility. The Reference Governor with Dynamic Constraint (RG-DC) starts from the asymptotically stable discrete-time model
Overshoot∗≈0.298473
Overshoot∗≈0.298474
with static output constraints Overshoot∗≈0.298475. The dynamic tracking constraint is
Overshoot∗≈0.298476
where Overshoot∗≈0.298477 if Overshoot∗≈0.298478, and Overshoot∗≈0.298479 otherwise. The corresponding dynamic maximal admissible set is
Overshoot∗≈0.298480
defined by constant future command Overshoot∗≈0.298481 and simultaneous satisfaction of Overshoot∗≈0.298482 and Overshoot∗≈0.298483 for all Overshoot∗≈0.298484 (Freiheit et al., 2020).
The online law computes
Overshoot∗≈0.298485
with Overshoot∗≈0.298486 chosen so that the current pair Overshoot∗≈0.298487 remains inside the time-varying polyhedral MAS. In the basic RG-DC,
Overshoot∗≈0.298488
so the maximal overshoot above the current reference is zero. If one permits up to Overshoot∗≈0.298489 of overshoot by replacing Overshoot∗≈0.298490 with Overshoot∗≈0.298491, the same construction enforces
Overshoot∗≈0.298492
The paper further states invariance, recursive feasibility, BIBO stability, and convergence for constant references, and observes that RG-DC completely suppresses the resonant peak of an under-damped loop, acting like a novel anti-resonant low-pass filter (Freiheit et al., 2020).
7. Overshoot in inflation after Coleman–De Luccia tunneling
Dutta, Vaudrevange, and Westphal study overshoot of the inflaton after CDL tunneling in an open FRW universe. For monomial exit potentials
Overshoot∗≈0.298493
with Overshoot∗≈0.298494 and Overshoot∗≈0.298495, curvature dominates at early times, Overshoot∗≈0.298496 and Overshoot∗≈0.298497, so the field obeys
Overshoot∗≈0.298498
After reaching Overshoot∗≈0.298499 it enters the plateau
R0∗≈2.15100
and the overshoot distance is
R0∗≈2.15101
The coefficient of R0∗≈2.15102 is universal for R0∗≈2.15103, while the R0∗≈2.15104 term decreases with R0∗≈2.15105 (Dutta et al., 2011).
The paper gives explicit formulas and bounds for the low-power cases. For R0∗≈2.15106,
R0∗≈2.15107
For R0∗≈2.15108,
R0∗≈2.15109
For R0∗≈2.15110,
R0∗≈2.15111
The broad statement is that for R0∗≈2.15112 the overshoot is bounded from above by the width of the steep barrier traversed after emerging from tunneling and before reaching a slow-roll region of the potential (Dutta et al., 2011).
For R0∗≈2.15113 the behavior changes qualitatively. At R0∗≈2.15114 the exact solution is
R0∗≈2.15115
for which R0∗≈2.15116 as R0∗≈2.15117. More generally, for any monomial with R0∗≈2.15118, the combination of a steeper outer potential and Hubble friction R0∗≈2.15119 brings R0∗≈2.15120 before or exactly at R0∗≈2.15121, so overshooting is entirely absent (Dutta et al., 2011).
The result extends to binomials and then to full power series,
R0∗≈2.15122
with matching point
R0∗≈2.15123
The overshoot is again controlled by the lowest non-zero monomial above the plateau,
R0∗≈2.15124
If one allows arbitrary finite initial speed after tunneling, the early-time equation
R0∗≈2.15125
implies rapid redshifting of R0∗≈2.15126, so the same bounds remain valid. The stated cosmological implication is that, in a landscape populated by CDL tunneling, small-field models suffer no parametrically large overshoot, and for exit potentials of order R0∗≈2.15127 they have zero classical overshoot (Dutta et al., 2011).