Inactive
Inactive[f]
is an inactive form of f.
Details
- Inactive[f][args] is effectively a purely symbolic form of f[args], in which no evaluation associated with f is done.
- Inactive is conveniently inserted into expressions using Inactivate.
- Inactive[f] displays in StandardForm, with f or any special output form associated with f shown in gray.
- Inactive does not affect TraditionalForm.
- Inactive has the attribute HoldFirst and does not evaluate its first argument.
- Inactive[atom] gives atom for atoms other than symbols.
Examples
open allclose allBasic Examples (3)
Inactive Length:
Inactivate Plus:
Display equality of activated and inactivated forms:
Inactive objects are grayed out in StandardForm:
But not in TraditionalForm:
Scope (13)
Basic Uses (5)
Define an inactive expression:
Evaluate the expression using Activate:
Create an inactive expression using Inactivate:
Expression with two inactive terms:
Formal Operations (5)
Applications (25)
Basic Identities (4)
Function Identities (3)
Calculus Identities (9)
Show identities, including Leibniz's rule for differentiating integrals:
Finite and infinite continued fractions:
Apply DifferenceDelta to an inactive sum:
This is significantly faster than the evaluated version:
Formula for summation by parts:
Verify the formula in a special case:
Interchange the order of summation and integration:
Evaluate both sides of the identity:
Obtain the same result using the corresponding sum:
The product rule for the Laplacian:
Vector identities for three-vectors u, v, and w:
Antisymmetry of the cross product:
Derive Identities (5)
The basic commutation trick for differentiating under the integral or summation sign:
Derive a closed form for by differentiating with respect to at :
Now integrate and then differentiate with respect to at :
Derive a closed form for by differentiating with respect to at zero:
is first integrated and then differentiated with respect to at zero:
Derive a closed form for by differentiating with respect to at :
Compute and then differentiate:
Derive a closed form for by differentiating wrt at :
Solve Differential Equations (2)
Solution for the three-dimensional Laplace equation in inactive integral form:
Obtain a particular solution by specifying the function f:
Maxwell's equations in natural Lorentz–Heaviside units:
Take the curl of Ampere's law in a vacuum ( and ):
Interchange order of differentiation:
Activate the equation, resulting in the wave equation for the magnetic field:
Derive a Least-Squares Solution (1)
Properties & Relations (5)
Inactive expressions can be created using Inactivate:
Inactive expressions can be evaluated using Activate:
Inactive creates inactive forms of symbols and allows parts of expressions to be inactive:
Hold maintains the expression in unevaluated form, and all parts are inactive:
Compare an inactive expression with the corresponding FullForm:
Inactive prevents the attributes of its argument from having any effect:
Normally, the Listable attribute would cause f to thread over its arguments:
Possible Issues (1)
Text
Wolfram Research (2014), Inactive, Wolfram Language function, https://reference.wolfram.com/language/ref/Inactive.html.
CMS
Wolfram Language. 2014. "Inactive." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/Inactive.html.
APA
Wolfram Language. (2014). Inactive. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/Inactive.html