UnitStep
Details
- Some transformations are done automatically when UnitStep appears in a product of terms.
- UnitStep provides a convenient way to represent piecewise continuous functions.
- UnitStep has attribute Orderless .
- For exact numeric quantities, UnitStep internally uses numerical approximations to establish its result. This process can be affected by the setting of the global variable $MaxExtraPrecision .
- UnitStep [] is 1.
- UnitStep automatically threads over lists. »
Examples
open all close allBasic Examples (4)
Evaluate numerically:
Plot in one dimension:
Plot in two dimensions:
UnitStep is a piecewise function:
Scope (34)
Numerical Evaluation (6)
Evaluate numerically:
UnitStep always returns an exact result:
Evaluate efficiently at high precision:
UnitStep can deal with real‐valued intervals:
Compute the elementwise values of an array using automatic threading:
Or compute the matrix UnitStep function using MatrixFunction :
Compute average-case statistical intervals using Around :
Specific Values (4)
Value at zero:
Value at infinity:
Evaluate for symbolic parameters:
Find a value of x for which the UnitStep [x]=1:
Visualization (4)
Function Properties (10)
Function domain of UnitStep :
It is restricted to real inputs:
Function range of UnitStep :
UnitStep has a jump discontinuity at the point :
UnitStep is not an analytic function:
It has both singularities and discontinuities:
UnitStep is nondecreasing:
UnitStep is not injective:
UnitStep is not surjective:
UnitStep is non-negative:
UnitStep is neither convex nor concave:
TraditionalForm formatting:
Differentiation and Integration (6)
First derivative with respect to x:
All higher-order derivatives the same:
First derivative with respect to z:
Compute the indefinite integral using Integrate :
Verify the anti-derivative away from the singular point:
Definite integral:
Integral over an infinite domain:
Integral Transforms (4)
FourierTransform of UnitStep :
Find the LaplaceTransform of UnitStep :
The convolution of UnitStep with itself:
Applications (8)
Generate a square wave:
Compute a step response for a continuous-time system:
Using transform methods:
Compute a step response for a discrete-time system:
Using transform methods:
Solve the time‐independent Schrödinger equation with piecewise analytic potential:
This gives the probability of the random variable being in the interval :
Here is the resulting probability plotted:
Construct the Walsh function:
Define a Bose–Einstein and a Maxwell–Boltzmann distribution function with UnitStep and Exp :
Plot the distributions:
Find the representation of a mathematical expression with UnitStep in terms of FoxH :
Properties & Relations (4)
The derivative of UnitStep is a piecewise function:
The derivative of HeavisideTheta is a distribution:
Expand into UnitStep of linear factors:
Convert into Piecewise :
Integrate over finite and infinite domains:
Possible Issues (3)
Symbolic preprocessing of functions containing UnitStep can be time‐consuming:
Limit does not give UnitStep as a limit of smooth functions:
Differentiating Abs does not yield UnitStep :
Use RealAbs to get a derivative of absolute value on the reals:
But for the origin, where the derivative does not exist, this is equivalent to an expression in UnitStep :
See Also
UnitBox RealSign Positive HeavisideTheta DiscreteDelta KroneckerDelta Unitize Boole Piecewise LogisticSigmoid Ramp
Function Repository: SmoothStep SmootherStep RationalSmoothStep
Related Guides
Related Links
History
Introduced in 1999 (4.0) | Updated in 2007 (6.0)
Text
Wolfram Research (1999), UnitStep, Wolfram Language function, https://reference.wolfram.com/language/ref/UnitStep.html (updated 2007).
CMS
Wolfram Language. 1999. "UnitStep." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2007. https://reference.wolfram.com/language/ref/UnitStep.html.
APA
Wolfram Language. (1999). UnitStep. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/UnitStep.html
BibTeX
@misc{reference.wolfram_2025_unitstep, author="Wolfram Research", title="{UnitStep}", year="2007", howpublished="\url{https://reference.wolfram.com/language/ref/UnitStep.html}", note=[Accessed: 16-November-2025]}
BibLaTeX
@online{reference.wolfram_2025_unitstep, organization={Wolfram Research}, title={UnitStep}, year={2007}, url={https://reference.wolfram.com/language/ref/UnitStep.html}, note=[Accessed: 16-November-2025]}