represents the triangle distribution
which is nonzero for
.
HeavisideLambda[x1,x2,…]
represents the multidimensional triangle distribution
which is nonzero for
.
HeavisideLambda
represents the triangle distribution
which is nonzero for
.
HeavisideLambda[x1,x2,…]
represents the multidimensional triangle distribution
which is nonzero for
.
Details
- HeavisideLambda[x] is equivalent to Convolve[HeavisidePi[t],HeavisidePi[t],t,x].
- HeavisideLambda can be used in derivatives, integrals, integral transforms, and differential equations.
- HeavisideLambda has attribute Orderless.
Examples
open all close allBasic Examples (4)
HeavisideLambda[0.8]Plot[HeavisideLambda[x], {x, -2, 2}]Plot3D[HeavisideLambda[x, y], {x, -1, 1}, {y, -1, 1}]Higher derivatives involve DiracDelta distributions:
D[HeavisideLambda[x], {x, 2}]Scope (38)
Numerical Evaluation (7)
HeavisideLambda[-1]HeavisideLambda[1 / 4]HeavisideLambda[1, Pi, 5.3]N[HeavisideLambda[5 / 17], 50]The precision of the output tracks the precision of the input:
HeavisideLambda[0.3333333333333333333]HeavisideLambda[1.2]Evaluate efficiently at high precision:
HeavisideLambda[4 / 7`100]//TimingHeavisideLambda[17 / 91`100000000];//TimingHeavisideLambda threads over lists:
HeavisideLambda[{-3, -1, 0, 1 / 3, 1}]Compute average-case statistical intervals using Around:
HeavisideLambda[ Around[1 / 2, 0.01]]Compute the elementwise values of an array:
HeavisideLambda[{{-1, 0}, {-1 / 2, 1 / 2}}]Or compute the matrix HeavisideLambda function using MatrixFunction:
MatrixFunction[HeavisideLambda, {{-1, 0}, {-1 / 2, 1 / 2}}]Specific Values (4)
Values of HeavisideLambda at fixed points:
Table[HeavisideLambda[n ], {n, -1, 1, 1 / 3}]HeavisideLambda[0]FunctionExpand[HeavisideLambda[x]]Find a value of x for which the HeavisideLambda[x]=0.6:
xval = x /. FindRoot[HeavisideLambda[x] == 0.6, {x, 0.3}]Plot[HeavisideLambda[x], {x, -2, 2}, Epilog -> Style[Point[{xval, HeavisideLambda[xval]}], PointSize[Large], Red], ExclusionsStyle -> Dotted]Visualization (4)
Plot the HeavisideLambda function:
Plot[HeavisideLambda[x], {x, -2, 2}]Visualize scaled HeavisideLambda functions:
Plot[{HeavisideLambda[x], HeavisideLambda[x / 2], HeavisideLambda[2x]}, {x, -3, 3}, PlotLegends -> "Expressions"]Visualize the composition of HeavisideLambda with a periodic function:
Plot[HeavisideLambda[Sin[x]], {x, -2Pi, 2Pi}]Plot HeavisideLambda in three dimensions:
Plot3D[HeavisideLambda[x, y], {x, -1.5, 1.5}, {y, -1.5, 1.5}, ColorFunction -> "SouthwestColors", Exclusions -> None, PlotRange -> All]Function Properties (11)
Function domain of HeavisideLambda:
FunctionDomain[HeavisideLambda[x], x]It is restricted to real inputs:
FunctionDomain[HeavisideLambda[x], x, Complexes]Function range of HeavisideLambda:
FunctionRange[HeavisideLambda[x], x, y]HeavisideLambda is an even function:
HeavisideLambda[-x]The area of HeavisideLambda is 1:
Integrate[HeavisideLambda[x], {x, -∞, ∞}]HeavisideLambda has singularities:
FunctionSingularities[HeavisideLambda[x], x]However, it is continuous everywhere:
FunctionContinuous[HeavisideLambda[x], x]Verify the claim at one of its singular points:
Underscript[, x -> 0]HeavisideLambda[x] == HeavisideLambda[0]HeavisideLambda is neither nonincreasing nor nondecreasing:
FunctionMonotonicity[HeavisideLambda[x], x]HeavisideLambda is not injective:
FunctionInjective[HeavisideLambda[x], x]Plot[{HeavisideLambda[x], .5}, {x, -2, 2}, PlotStyle -> {Thick}]HeavisideLambda is not surjective:
FunctionSurjective[HeavisideLambda[x], x]Plot[{HeavisideLambda[x], -1}, {x, -2, 2}, PlotStyle -> {Thick}]HeavisideLambda is non-negative:
FunctionSign[HeavisideLambda[x], x]HeavisideLambda is neither convex nor concave:
FunctionConvexity[HeavisideLambda[x], x]TraditionalForm typesetting:
HeavisideLambda[x]//TraditionalFormDifferentiation (4)
Differentiate the univariate HeavisideLambda:
D[HeavisideLambda[x], x]Higher derivatives with respect to x:
Table[D[HeavisideLambda[x], {x, k}], {k, 2, 4}]//FullSimplifyDifferentiate the multivariate HeavisideLambda:
D[HeavisideLambda[x, y, z], z]Differentiate a composition involving HeavisideLambda:
D[HeavisideLambda[x, f[y], z], y]Integration (4)
Integrate over finite domains:
Integrate[HeavisideLambda[x], {x, 0, y}, Assumptions -> y > 0]Integrate[HeavisideLambda[x^2 - x]Cos[x], {x, 0, 5}]Integrate over infinite domains:
Integrate[HeavisideLambda[x] Exp[-x ^ 2], {x, -Infinity, Infinity}]NIntegrate[HeavisideLambda[ Cos[x]] Sin[x], {x, 0, (2π/3), 5}]Integrate expressions containing symbolic derivatives of HeavisideLambda:
Integrate[HeavisideLambda'''[x - a] f[x], {x, -Infinity, Infinity}, Assumptions -> a∈Reals]Integral Transforms (4)
FourierTransform of HeavisideLambda is a squared Sinc function:
FourierTransform[HeavisideLambda[x], x, t, FourierParameters -> {1, 1}]Plot[%, {t, -15, 15}]FourierSeries[HeavisideLambda[x], x, 5]// FullSimplifyPlot[{%, HeavisideLambda[x]}, {x, -2, 2}, Exclusions -> None]Find the LaplaceTransform of HeavisideLambda:
LaplaceTransform[HeavisideLambda[x], x, t]Plot[%, {t, -3, 3}, PlotRange -> All]The convolution of HeavisideLambda with HeavisidePi:
Convolve[HeavisideLambda[x], HeavisidePi[x], x, y]Plot[%, {y, -2, 2}]Applications (2)
Integrate a function involving HeavisideLambda symbolically and numerically:
Plot[Tanh[x] HeavisideLambda[3x - 1], {x, 0, 1}]Integrate[Tanh[x] HeavisideLambda[3x - 1], {x, -1, 1}]N[%]NIntegrate[Tanh[x]UnitTriangle[3x - 1], {x, -1, 1}]Visualize discontinuities in the wavelet domain:
data = Table[HeavisideLambda[x], {x, -2, 2, 4 / 1023}];ListLinePlot[data]Detail coefficients in the region of discontinuities have larger values:
dwd = DiscreteWaveletTransform[data, DaubechiesWavelet[3], 5, Padding -> "Reflected"];WaveletScalogram[dwd, {___, 1}, Method -> "Inverse" -> True, ColorFunction -> "BlueGreenYellow"]Properties & Relations (2)
The derivative of HeavisideLambda is a distribution:
D[HeavisideLambda[x], x]At higher orders, the DiracDelta distribution appears:
D[HeavisideLambda[x], {x, 2}]The derivative of UnitTriangle is a piecewise function:
D[UnitTriangle[x], x]HeavisideLambda can be expressed in terms of HeavisideTheta:
FunctionExpand[HeavisideLambda[x]]See Also
Related Guides
Related Links
History
Text
Wolfram Research (2008), HeavisideLambda, Wolfram Language function, https://reference.wolfram.com/language/ref/HeavisideLambda.html.
CMS
Wolfram Language. 2008. "HeavisideLambda." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/HeavisideLambda.html.
APA
Wolfram Language. (2008). HeavisideLambda. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/HeavisideLambda.html
BibTeX
@misc{reference.wolfram_2026_heavisidelambda, author="Wolfram Research", title="{HeavisideLambda}", year="2008", howpublished="\url{https://reference.wolfram.com/language/ref/HeavisideLambda.html}", note=[Accessed: 13-June-2026]}
BibLaTeX
@online{reference.wolfram_2026_heavisidelambda, organization={Wolfram Research}, title={HeavisideLambda}, year={2008}, url={https://reference.wolfram.com/language/ref/HeavisideLambda.html}, note=[Accessed: 13-June-2026]}