LogisticSigmoid [z]
gives the logistic sigmoid function.
LogisticSigmoid
LogisticSigmoid [z]
gives the logistic sigmoid function.
Details
- Mathematical function, suitable for both symbolic and numeric manipulation.
- In TraditionalForm , the logistic sigmoid function is sometimes denoted as .
- The logistic function is a solution to the differential equation .
- LogisticSigmoid [z] has no branch cut discontinuities.
- LogisticSigmoid can be evaluated to arbitrary numerical precision.
- LogisticSigmoid automatically threads over lists. »
- LogisticSigmoid can be used with Interval and CenteredInterval objects. »
Examples
open all close allBasic Examples (5)
Evaluate numerically:
Plot over a subset of the reals:
Plot over a subset of the complexes:
Series expansion at the origin:
The expansion of the function:
Scope (36)
Numerical Evaluation (6)
Evaluate numerically:
Evaluate to high precision:
The precision of the output tracks the precision of the input:
Complex number input:
Evaluate efficiently at high precision:
Compute worst-case guaranteed intervals using Interval and CenteredInterval objects:
Or compute average-case statistical intervals using Around :
Compute the elementwise values of an array using automatic threading:
Or compute the matrix LogisticSigmoid function using MatrixFunction :
Specific Values (4)
The value of LogisticSigmoid at 2 πI n for integer n is 1/2:
Values at infinity:
Simple exact values are generated automatically:
More complicated cases require explicit use of FunctionExpand :
Find a value of for which the TemplateBox[{x}, LogisticSigmoid]=0.8` using Solve :
Substitute in the result:
Visualize the result:
Visualization (3)
Plot the LogisticSigmoid [x] function:
Plot the real part of TemplateBox[{z}, LogisticSigmoid]:
Plot the imaginary part of TemplateBox[{z}, LogisticSigmoid]:
Polar plot with TemplateBox[{phi}, LogisticSigmoid]:
Function Properties (10)
LogisticSigmoid is defined for all real and complex values:
LogisticSigmoid achieves all values between 0 and 1 on the reals:
The range for complex values:
LogisticSigmoid has the mirror property TemplateBox[{{z, }}, LogisticSigmoid]=TemplateBox[{z}, LogisticSigmoid]:
LogisticSigmoid is an analytic function of x:
It has no singularities or discontinuities:
LogisticSigmoid is nondecreasing:
LogisticSigmoid is injective:
LogisticSigmoid is not surjective:
LogisticSigmoid is non-negative:
LogisticSigmoid is neither convex nor concave:
TraditionalForm formatting:
Differentiation (3)
First derivative with respect to z:
Higher derivatives with respect to z:
Plot the higher derivatives with respect to z:
Formula for the ^(th) derivative with respect to z:
Integration (3)
Compute the indefinite integral using Integrate :
Verify the anti-derivative:
Definite integral:
More integrals:
Series Expansions (3)
Function Representations (4)
LogisticSigmoid can be represented in terms of Exp :
Series representation:
LogisticSigmoid can be represented in terms of MeijerG :
LogisticSigmoid obeys the logistic differential equation :
Applications (1)
Write a specific solution to the dimensionless logistic equation using LogisticSigmoid :
See Also
Exp LogisticDistribution UnitStep HeavisideTheta
Function Repository: Logit SmoothStep RationalSmoothStep
Related Guides
Related Links
History
Text
Wolfram Research (2014), LogisticSigmoid, Wolfram Language function, https://reference.wolfram.com/language/ref/LogisticSigmoid.html.
CMS
Wolfram Language. 2014. "LogisticSigmoid." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/LogisticSigmoid.html.
APA
Wolfram Language. (2014). LogisticSigmoid. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/LogisticSigmoid.html
BibTeX
@misc{reference.wolfram_2025_logisticsigmoid, author="Wolfram Research", title="{LogisticSigmoid}", year="2014", howpublished="\url{https://reference.wolfram.com/language/ref/LogisticSigmoid.html}", note=[Accessed: 16-November-2025]}
BibLaTeX
@online{reference.wolfram_2025_logisticsigmoid, organization={Wolfram Research}, title={LogisticSigmoid}, year={2014}, url={https://reference.wolfram.com/language/ref/LogisticSigmoid.html}, note=[Accessed: 16-November-2025]}