FunctionMonotonicity[f,x]
finds the monotonicity of the function f with the variable x over the reals.
FunctionMonotonicity[f,x,dom]
finds the monotonicity of f when x is restricted to the domain dom.
FunctionMonotonicity[{f,cons},x,dom]
gives the monotonicity of f when x is restricted by the constraints cons.
 
     
   FunctionMonotonicity
FunctionMonotonicity[f,x]
finds the monotonicity of the function f with the variable x over the reals.
FunctionMonotonicity[f,x,dom]
finds the monotonicity of f when x is restricted to the domain dom.
FunctionMonotonicity[{f,cons},x,dom]
gives the monotonicity of f when x is restricted by the constraints cons.
Details and Options
 
     
   - Monotonicity is also known as increasing, decreasing, non-decreasing, non-increasing, strictly increasing and strictly decreasing.
- By default, the following definitions are used:
- 
      
       +1 non-decreasing, i.e.  for all for all  0 constant, i.e.  for all for all  -1 non-increasing, i.e.  for all for all  Indeterminate neither non-decreasing nor non-increasing 
- The constant function is both non-decreasing and non-increasing.
- With the setting StrictInequalitiesTrue, the following definitions are used:
- 
      
       +1 increasing, i.e.  for all for all  -1 decreasing, i.e.  for all for all  Indeterminate neither increasing nor decreasing 
- Possible values for dom include: Reals, Integers, PositiveReals, PositiveIntegers, etc. The default is Reals.
- The function f should be a real-valued function for all x in the domain dom that satisfy the constraints cons.
- cons can contain equations, inequalities or logical combinations of these.
- The following options can be given:
- 
      
      Assumptions $Assumptions assumptions on parameters GenerateConditions True whether to generate conditions on parameters PerformanceGoal $PerformanceGoal whether to prioritize speed or quality StrictInequalities True whether to require strict monotonicity 
- Possible settings for GenerateConditions include:
- 
      
      Automatic nongeneric conditions only True all conditions False no conditions None return unevaluated if conditions are needed 
- Possible settings for PerformanceGoal are "Speed" and "Quality".
Examples
open all close allBasic Examples (3)
Scope (5)
Monotonicity over unrestricted reals:
A function that is not real valued has Indeterminate monotonicity:
The function is real valued and increasing for positive  :
:
Monotonicity with constraints on the variable:
Strict monotonicity of a function:
![TemplateBox[{x}, Floor] TemplateBox[{x}, Floor]](Files/FunctionMonotonicity.en/19.png) is non-decreasing, but not strictly increasing.
 is non-decreasing, but not strictly increasing. ![TemplateBox[{x}, Floor]+x TemplateBox[{x}, Floor]+x](Files/FunctionMonotonicity.en/20.png) is strictly increasing:
 is strictly increasing:
Options (5)
Assumptions (1)
FunctionMonotonicity gives a conditional answer here:
GenerateConditions (2)
By default, FunctionMonotonicity may generate conditions on symbolic parameters:
With GenerateConditionsNone, FunctionMonotonicity fails instead of giving a conditional result:
This returns a conditionally valid result without stating the condition:
By default, all conditions are reported:
With GenerateConditionsAutomatic, conditions that are generically true are not reported:
PerformanceGoal (1)
Use PerformanceGoal to avoid potentially expensive computations:
The default setting uses all available techniques to try to produce a result:
StrictInequalities (1)
By default, FunctionMonotonicity computes the non-strict monotonicity:
With StrictInequalitiesTrue, FunctionMonotonicity computes the strict monotonicity:
Ramp[x]+1 is non-decreasing, but is not strictly increasing. Ramp[x]+x is strictly increasing:
Applications (19)
Basic Cases (5)
Positive powers  are all non-decreasing for the positive reals
 are all non-decreasing for the positive reals ![TemplateBox[{}, PositiveReals] TemplateBox[{}, PositiveReals]](Files/FunctionMonotonicity.en/23.png) :
: 
This shows that the whole family is non-decreasing:
In fact, they are all increasing:
Negative powers  are non-increasing for the positive reals
 are non-increasing for the positive reals ![TemplateBox[{}, PositiveReals] TemplateBox[{}, PositiveReals]](Files/FunctionMonotonicity.en/25.png) :
: 
This shows that the whole family is decreasing:
Exponential functions  are increasing for
 are increasing for  and decreasing for
 and decreasing for  :
: 
Trigonometric functions are non-monotonic over the reals:
Combination Cases (5)
The sum of functions with monotonicity  has monotonicity
 has monotonicity  :
:
The sum has the same monotonicity:
The product of non-negative non-decreasing functions is non-decreasing:
Their product is also non-decreasing:
The composition of non-decreasing functions is non-decreasing:
Their compositions are also non-decreasing:
The inverse of an increasing function is increasing:
The inverse is also increasing:
The range of a non-decreasing function  on an interval
 on an interval  is
 is  :
:
For comparison, compute the range using FunctionRange:
Calculus (4)
 is non-decreasing and bounded from above for
 is non-decreasing and bounded from above for  :
:
The limit of  at
 at  equals the supremum of
 equals the supremum of  :
:
Terms of the series are non-negative, hence the partial sums are increasing:
The partial sums are bounded from above, hence the series converges:
Use Sum to compute the sum of the series:
If  is non-negative, then
 is non-negative, then  is a non-decreasing function of
 is a non-decreasing function of  :
:
Write a differentiable function as a sum of an increasing function and a decreasing function:
Check whether the functions need to be adjusted by a constant:
Probability (3)
CDF is always non-decreasing:
SurvivalFunction is always non-increasing:
Quantile is always non-decreasing in  :
:
Equation Solving and Optimization (2)
If  is increasing and continuous in
 is increasing and continuous in  and
 and  , then
, then  has exactly one root in
 has exactly one root in  :
:
Use Solve to find the root:
Compute the maximum of  when
 when  is a non-decreasing function:
 is a non-decreasing function:
Properties & Relations (2)
The sum and composition of non-decreasing functions are non-decreasing:
The derivative of a non-decreasing function is non-negative:
Use D to compute the derivative:
Use FunctionSign to verify that the derivative is non-negative:
See Also
Related Guides
History
Text
Wolfram Research (2020), FunctionMonotonicity, Wolfram Language function, https://reference.wolfram.com/language/ref/FunctionMonotonicity.html.
CMS
Wolfram Language. 2020. "FunctionMonotonicity." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/FunctionMonotonicity.html.
APA
Wolfram Language. (2020). FunctionMonotonicity. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/FunctionMonotonicity.html
BibTeX
@misc{reference.wolfram_2025_functionmonotonicity, author="Wolfram Research", title="{FunctionMonotonicity}", year="2020", howpublished="\url{https://reference.wolfram.com/language/ref/FunctionMonotonicity.html}", note=[Accessed: 31-October-2025]}
BibLaTeX
@online{reference.wolfram_2025_functionmonotonicity, organization={Wolfram Research}, title={FunctionMonotonicity}, year={2020}, url={https://reference.wolfram.com/language/ref/FunctionMonotonicity.html}, note=[Accessed: 31-October-2025]}

![TemplateBox[{x}, Ceiling] TemplateBox[{x}, Ceiling]](Files/FunctionMonotonicity.en/29.png)








