Inactivate[expr]
replaces all instances of f with Inactive[f] for symbols f used as heads in expr.
Inactivate[expr,patt]
inactivates all symbols in expr that match the pattern patt.


Inactivate
Inactivate[expr]
replaces all instances of f with Inactive[f] for symbols f used as heads in expr.
Inactivate[expr,patt]
inactivates all symbols in expr that match the pattern patt.
Details and Options

- Inactivate has attribute HoldFirst, and symbols in expr are inactivated before evaluation.
- With the option setting Heads->False, Inactivate does not enter heads of expressions and inactivate their parts.
- By default, certain semantically important heads are not inactivated. Common examples include List, Rule and Blank.
Examples
open all close allBasic Examples (3)
Scope (5)
Inactivate all symbols except Integrate in an expression:
Options (1)
Heads (1)
By default, Inactivate will make heads inactive, even inside compound heads:
With the setting Heads->False, inactivation does not proceed inside compound heads:
Applications (5)
Define a trigonometric expression:
Activate different trigonometric functions:
Define , leaving both the derivative and integral inactive:
Differentiate the integral without evaluating the integral:
Activate the integral to compute the final result:
Integrate without performing the differentiation:
Activate the differentiation to compute the final result:
The results are mathematically the same:
Show identities including Leibniz's rule for differentiating integrals:
Properties & Relations (6)
Activate is the inverse of Inactivate:
Inactivate replaces specific symbols with their inactive forms:
Activate replaces all instances of inactive symbols with their active forms:
Inactivate maintains symbols in inactive form and allows parts of expressions to be inactive:
Hold maintains expressions in unevaluated form, and all parts are inactive:
Compare an inactive expression with the corresponding FullForm:
Inactivate is an idempotent operator:
Certain heads are not inactivated by default, including List, Rule () and Blank (_):
Using Replace at all levels can inactivate all heads in an expression:
Possible Issues (1)
As compound heads have no attributes, the use of Inactivate can lead to evaluation leaks:
Normally, the HoldAll attribute of Sum would prevent the k from evaluating:
Related Guides
Related Workflows
- Handle Code Symbolically
History
Text
Wolfram Research (2014), Inactivate, Wolfram Language function, https://reference.wolfram.com/language/ref/Inactivate.html.
CMS
Wolfram Language. 2014. "Inactivate." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/Inactivate.html.
APA
Wolfram Language. (2014). Inactivate. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/Inactivate.html
BibTeX
@misc{reference.wolfram_2025_inactivate, author="Wolfram Research", title="{Inactivate}", year="2014", howpublished="\url{https://reference.wolfram.com/language/ref/Inactivate.html}", note=[Accessed: 13-August-2025]}
BibLaTeX
@online{reference.wolfram_2025_inactivate, organization={Wolfram Research}, title={Inactivate}, year={2014}, url={https://reference.wolfram.com/language/ref/Inactivate.html}, note=[Accessed: 13-August-2025]}