Integrating function with /; in its definitionHow to make InverseFunction work on function defined with...

PTiJ: How should animals pray?

Quitting employee has privileged access to critical information

Should we avoid writing fiction about historical events without extensive research?

Paper published similar to PhD thesis

Create chunks from an array

Remove object from array based on array of some property of that object

What does "rhumatis" mean?

How spaceships determine each other's mass in space?

Computing the volume of a simplex-like object with constraints

Is "cogitate" an appropriate word for this?

PTIJ: Mouthful of Mitzvos

Is there a way to find out the age of climbing ropes?

Was it really inappropriate to write a pull request for the company I interviewed with?

Are Wave equations equivalent to Maxwell equations in free space?

What is the oldest European royal house?

Giving a talk in my old university, how prominently should I tell students my salary?

Under what conditions would I NOT add my Proficiency Bonus to a Spell Attack Roll (or Saving Throw DC)?

Problems with rounding giving too many digits

Does the US political system, in principle, allow for a no-party system?

What is better: yes / no radio, or simple checkbox?

3.5% Interest Student Loan or use all of my savings on Tuition?

Why are special aircraft used for the carriers in the United States Navy?

Integrating function with /; in its definition

What's the best tool for cutting holes into duct work?



Integrating function with /; in its definition


How to make InverseFunction work on function defined with restriction on argumentsIntegrating a periodic functionHow to Integrate trivial products of DiracDeltaIntegrating expressions with several terms and delta functionsSubstitute a function's definition for its nameMathematica `Integrate` evaluates some integrals only with some specific scaling factorPlotting a function involving Nsolve in its definitionDefinition of a periodic function doesn't work when given as the forcing function of an ODEProblem with pendulum code cant get to plot Mathematica 11.3Define Function using another Function and plot













3












$begingroup$


why



f[x_ /; x>=0]:=x;
Integrate[f[x] ,{x,0,2 Pi}]


return unevaluated? Notice that the above definition of f[x] works OK with other Mathematica functions, such as Plot



Plot[f[x], {x, 0, 2 Pi}]


Mathematica graphics



While the following works with Integrate



f[x_]:=x;
Integrate[f[x] ,{x,0,2 Pi}]


I am using version 11.3 on windows.










share|improve this question











$endgroup$








  • 4




    $begingroup$
    It's better to use ConditionalExpression, e.g., Integrate[ConditionalExpression[x, x>0], {x, 0, 2Pi}]
    $endgroup$
    – Carl Woll
    4 hours ago
















3












$begingroup$


why



f[x_ /; x>=0]:=x;
Integrate[f[x] ,{x,0,2 Pi}]


return unevaluated? Notice that the above definition of f[x] works OK with other Mathematica functions, such as Plot



Plot[f[x], {x, 0, 2 Pi}]


Mathematica graphics



While the following works with Integrate



f[x_]:=x;
Integrate[f[x] ,{x,0,2 Pi}]


I am using version 11.3 on windows.










share|improve this question











$endgroup$








  • 4




    $begingroup$
    It's better to use ConditionalExpression, e.g., Integrate[ConditionalExpression[x, x>0], {x, 0, 2Pi}]
    $endgroup$
    – Carl Woll
    4 hours ago














3












3








3





$begingroup$


why



f[x_ /; x>=0]:=x;
Integrate[f[x] ,{x,0,2 Pi}]


return unevaluated? Notice that the above definition of f[x] works OK with other Mathematica functions, such as Plot



Plot[f[x], {x, 0, 2 Pi}]


Mathematica graphics



While the following works with Integrate



f[x_]:=x;
Integrate[f[x] ,{x,0,2 Pi}]


I am using version 11.3 on windows.










share|improve this question











$endgroup$




why



f[x_ /; x>=0]:=x;
Integrate[f[x] ,{x,0,2 Pi}]


return unevaluated? Notice that the above definition of f[x] works OK with other Mathematica functions, such as Plot



Plot[f[x], {x, 0, 2 Pi}]


Mathematica graphics



While the following works with Integrate



f[x_]:=x;
Integrate[f[x] ,{x,0,2 Pi}]


I am using version 11.3 on windows.







calculus-and-analysis function-construction






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited 37 mins ago









J. M. is computer-less

97.3k10303463




97.3k10303463










asked 4 hours ago









NasserNasser

58.1k489206




58.1k489206








  • 4




    $begingroup$
    It's better to use ConditionalExpression, e.g., Integrate[ConditionalExpression[x, x>0], {x, 0, 2Pi}]
    $endgroup$
    – Carl Woll
    4 hours ago














  • 4




    $begingroup$
    It's better to use ConditionalExpression, e.g., Integrate[ConditionalExpression[x, x>0], {x, 0, 2Pi}]
    $endgroup$
    – Carl Woll
    4 hours ago








4




4




$begingroup$
It's better to use ConditionalExpression, e.g., Integrate[ConditionalExpression[x, x>0], {x, 0, 2Pi}]
$endgroup$
– Carl Woll
4 hours ago




$begingroup$
It's better to use ConditionalExpression, e.g., Integrate[ConditionalExpression[x, x>0], {x, 0, 2Pi}]
$endgroup$
– Carl Woll
4 hours ago










1 Answer
1






active

oldest

votes


















5












$begingroup$

f[x_ /; x>=0]:=x means "if whatever>=0 rewrite f[whatever] as whatever. But that doesn't apply to f[x] when x is a symbol without a numerical value. Thus, f[x] simply remains f[x]. For abstracting the notion of a function with a break like this, use Piecewise or HeavisideTheta: Integrate understands what those mean.






share|improve this answer









$endgroup$













    Your Answer





    StackExchange.ifUsing("editor", function () {
    return StackExchange.using("mathjaxEditing", function () {
    StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
    StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
    });
    });
    }, "mathjax-editing");

    StackExchange.ready(function() {
    var channelOptions = {
    tags: "".split(" "),
    id: "387"
    };
    initTagRenderer("".split(" "), "".split(" "), channelOptions);

    StackExchange.using("externalEditor", function() {
    // Have to fire editor after snippets, if snippets enabled
    if (StackExchange.settings.snippets.snippetsEnabled) {
    StackExchange.using("snippets", function() {
    createEditor();
    });
    }
    else {
    createEditor();
    }
    });

    function createEditor() {
    StackExchange.prepareEditor({
    heartbeatType: 'answer',
    autoActivateHeartbeat: false,
    convertImagesToLinks: false,
    noModals: true,
    showLowRepImageUploadWarning: true,
    reputationToPostImages: null,
    bindNavPrevention: true,
    postfix: "",
    imageUploader: {
    brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
    contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
    allowUrls: true
    },
    onDemand: true,
    discardSelector: ".discard-answer"
    ,immediatelyShowMarkdownHelp:true
    });


    }
    });














    draft saved

    draft discarded


















    StackExchange.ready(
    function () {
    StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmathematica.stackexchange.com%2fquestions%2f192838%2fintegrating-function-with-in-its-definition%23new-answer', 'question_page');
    }
    );

    Post as a guest















    Required, but never shown

























    1 Answer
    1






    active

    oldest

    votes








    1 Answer
    1






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    5












    $begingroup$

    f[x_ /; x>=0]:=x means "if whatever>=0 rewrite f[whatever] as whatever. But that doesn't apply to f[x] when x is a symbol without a numerical value. Thus, f[x] simply remains f[x]. For abstracting the notion of a function with a break like this, use Piecewise or HeavisideTheta: Integrate understands what those mean.






    share|improve this answer









    $endgroup$


















      5












      $begingroup$

      f[x_ /; x>=0]:=x means "if whatever>=0 rewrite f[whatever] as whatever. But that doesn't apply to f[x] when x is a symbol without a numerical value. Thus, f[x] simply remains f[x]. For abstracting the notion of a function with a break like this, use Piecewise or HeavisideTheta: Integrate understands what those mean.






      share|improve this answer









      $endgroup$
















        5












        5








        5





        $begingroup$

        f[x_ /; x>=0]:=x means "if whatever>=0 rewrite f[whatever] as whatever. But that doesn't apply to f[x] when x is a symbol without a numerical value. Thus, f[x] simply remains f[x]. For abstracting the notion of a function with a break like this, use Piecewise or HeavisideTheta: Integrate understands what those mean.






        share|improve this answer









        $endgroup$



        f[x_ /; x>=0]:=x means "if whatever>=0 rewrite f[whatever] as whatever. But that doesn't apply to f[x] when x is a symbol without a numerical value. Thus, f[x] simply remains f[x]. For abstracting the notion of a function with a break like this, use Piecewise or HeavisideTheta: Integrate understands what those mean.







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered 4 hours ago









        John DotyJohn Doty

        7,32811124




        7,32811124






























            draft saved

            draft discarded




















































            Thanks for contributing an answer to Mathematica Stack Exchange!


            • Please be sure to answer the question. Provide details and share your research!

            But avoid



            • Asking for help, clarification, or responding to other answers.

            • Making statements based on opinion; back them up with references or personal experience.


            Use MathJax to format equations. MathJax reference.


            To learn more, see our tips on writing great answers.




            draft saved


            draft discarded














            StackExchange.ready(
            function () {
            StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmathematica.stackexchange.com%2fquestions%2f192838%2fintegrating-function-with-in-its-definition%23new-answer', 'question_page');
            }
            );

            Post as a guest















            Required, but never shown





















































            Required, but never shown














            Required, but never shown












            Required, but never shown







            Required, but never shown

































            Required, but never shown














            Required, but never shown












            Required, but never shown







            Required, but never shown







            Popular posts from this blog

            Why does my Macbook overheat and use so much CPU and energy when on YouTube?Why do so many insist on using...

            How to prevent page numbers from appearing on glossaries?How to remove a dot and a page number in the...

            Puerta de Hutt Referencias Enlaces externos Menú de navegación15°58′00″S 5°42′00″O /...