Is there a way to integrate the log of a function, f(x) in Matlab without defining eg l = log(f(x)?












3















I have the following code:



x = 0:0.001:2.5;

gamma_l = @(x) 2*x;


And I want to integrate the following:



integral( log(gamma_l), 0 , 0.6 )


But it gives me the error:




Undefined function 'log' for input arguments of type
'function_handle'.




I know that I could just define:



gamma_l_l = @(x) log(2*x);

integral( gamma_l_l, 0 , 0.6 )


Because it works in this way. However, I would like to know why the first case does not work. And if there is a way to integrate the function without defining a new function.






matlab integration







share|improve this question


















  • 1





    The first case does not work because log() requires numbers as inputs, and you are not giving it a number, you are giving it a function handle. The logarithm of a function handle is not defined.

    – Ander Biguri
    Nov 13 '18 at 16:07













  • Thanks, @Ander! So do you think that the most efficient (only) way is to define another function? Isn't there a way to define composite function inside the integral?

    – Tecon
    Nov 13 '18 at 16:11






  • 1





    Gnovice's answer is how you should handle this ;)

    – Ander Biguri
    Nov 13 '18 at 16:32
















3















I have the following code:



x = 0:0.001:2.5;

gamma_l = @(x) 2*x;


And I want to integrate the following:



integral( log(gamma_l), 0 , 0.6 )


But it gives me the error:




Undefined function 'log' for input arguments of type
'function_handle'.




I know that I could just define:



gamma_l_l = @(x) log(2*x);

integral( gamma_l_l, 0 , 0.6 )


Because it works in this way. However, I would like to know why the first case does not work. And if there is a way to integrate the function without defining a new function.






matlab integration







share|improve this question


















  • 1





    The first case does not work because log() requires numbers as inputs, and you are not giving it a number, you are giving it a function handle. The logarithm of a function handle is not defined.

    – Ander Biguri
    Nov 13 '18 at 16:07













  • Thanks, @Ander! So do you think that the most efficient (only) way is to define another function? Isn't there a way to define composite function inside the integral?

    – Tecon
    Nov 13 '18 at 16:11






  • 1





    Gnovice's answer is how you should handle this ;)

    – Ander Biguri
    Nov 13 '18 at 16:32














3












3








3








I have the following code:



x = 0:0.001:2.5;

gamma_l = @(x) 2*x;


And I want to integrate the following:



integral( log(gamma_l), 0 , 0.6 )


But it gives me the error:




Undefined function 'log' for input arguments of type
'function_handle'.




I know that I could just define:



gamma_l_l = @(x) log(2*x);

integral( gamma_l_l, 0 , 0.6 )


Because it works in this way. However, I would like to know why the first case does not work. And if there is a way to integrate the function without defining a new function.






matlab integration







share|improve this question














I have the following code:



x = 0:0.001:2.5;

gamma_l = @(x) 2*x;


And I want to integrate the following:



integral( log(gamma_l), 0 , 0.6 )


But it gives me the error:




Undefined function 'log' for input arguments of type
'function_handle'.




I know that I could just define:



gamma_l_l = @(x) log(2*x);

integral( gamma_l_l, 0 , 0.6 )


Because it works in this way. However, I would like to know why the first case does not work. And if there is a way to integrate the function without defining a new function.






matlab integration




matlab integration






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked Nov 13 '18 at 16:05









TeconTecon

183




183








  • 1





    The first case does not work because log() requires numbers as inputs, and you are not giving it a number, you are giving it a function handle. The logarithm of a function handle is not defined.

    – Ander Biguri
    Nov 13 '18 at 16:07













  • Thanks, @Ander! So do you think that the most efficient (only) way is to define another function? Isn't there a way to define composite function inside the integral?

    – Tecon
    Nov 13 '18 at 16:11






  • 1





    Gnovice's answer is how you should handle this ;)

    – Ander Biguri
    Nov 13 '18 at 16:32














  • 1





    The first case does not work because log() requires numbers as inputs, and you are not giving it a number, you are giving it a function handle. The logarithm of a function handle is not defined.

    – Ander Biguri
    Nov 13 '18 at 16:07













  • Thanks, @Ander! So do you think that the most efficient (only) way is to define another function? Isn't there a way to define composite function inside the integral?

    – Tecon
    Nov 13 '18 at 16:11






  • 1





    Gnovice's answer is how you should handle this ;)

    – Ander Biguri
    Nov 13 '18 at 16:32








1




1





The first case does not work because log() requires numbers as inputs, and you are not giving it a number, you are giving it a function handle. The logarithm of a function handle is not defined.

– Ander Biguri
Nov 13 '18 at 16:07







The first case does not work because log() requires numbers as inputs, and you are not giving it a number, you are giving it a function handle. The logarithm of a function handle is not defined.

– Ander Biguri
Nov 13 '18 at 16:07















Thanks, @Ander! So do you think that the most efficient (only) way is to define another function? Isn't there a way to define composite function inside the integral?

– Tecon
Nov 13 '18 at 16:11





Thanks, @Ander! So do you think that the most efficient (only) way is to define another function? Isn't there a way to define composite function inside the integral?

– Tecon
Nov 13 '18 at 16:11




1




1





Gnovice's answer is how you should handle this ;)

– Ander Biguri
Nov 13 '18 at 16:32





Gnovice's answer is how you should handle this ;)

– Ander Biguri
Nov 13 '18 at 16:32












1 Answer
1






active

oldest

votes


















5














Your variable gamma_l is an anonymous function, and the log function is not designed to accept function handles as an input. Instead, you need to define a second anonymous function that evaluates gamma_l for a given value, then passes the numeric result to log, like so:



result = integral(@(x) log(gamma_l(x)), 0, 0.6);





share|improve this answer

























    Your Answer






    StackExchange.ifUsing("editor", function () {
    StackExchange.using("externalEditor", function () {
    StackExchange.using("snippets", function () {
    StackExchange.snippets.init();
    });
    });
    }, "code-snippets");

    StackExchange.ready(function() {
    var channelOptions = {
    tags: "".split(" "),
    id: "1"
    };
    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: true,
    noModals: true,
    showLowRepImageUploadWarning: true,
    reputationToPostImages: 10,
    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%2fstackoverflow.com%2fquestions%2f53284969%2fis-there-a-way-to-integrate-the-log-of-a-function-fx-in-matlab-without-defini%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














    Your variable gamma_l is an anonymous function, and the log function is not designed to accept function handles as an input. Instead, you need to define a second anonymous function that evaluates gamma_l for a given value, then passes the numeric result to log, like so:



    result = integral(@(x) log(gamma_l(x)), 0, 0.6);





    share|improve this answer






























      5














      Your variable gamma_l is an anonymous function, and the log function is not designed to accept function handles as an input. Instead, you need to define a second anonymous function that evaluates gamma_l for a given value, then passes the numeric result to log, like so:



      result = integral(@(x) log(gamma_l(x)), 0, 0.6);





      share|improve this answer




























        5












        5








        5







        Your variable gamma_l is an anonymous function, and the log function is not designed to accept function handles as an input. Instead, you need to define a second anonymous function that evaluates gamma_l for a given value, then passes the numeric result to log, like so:



        result = integral(@(x) log(gamma_l(x)), 0, 0.6);





        share|improve this answer















        Your variable gamma_l is an anonymous function, and the log function is not designed to accept function handles as an input. Instead, you need to define a second anonymous function that evaluates gamma_l for a given value, then passes the numeric result to log, like so:



        result = integral(@(x) log(gamma_l(x)), 0, 0.6);






        share|improve this answer














        share|improve this answer



        share|improve this answer








        edited Nov 13 '18 at 16:14

























        answered Nov 13 '18 at 16:08









        gnovicegnovice

        116k13231335




        116k13231335






























            draft saved

            draft discarded




















































            Thanks for contributing an answer to Stack Overflow!


            • 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.


            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%2fstackoverflow.com%2fquestions%2f53284969%2fis-there-a-way-to-integrate-the-log-of-a-function-fx-in-matlab-without-defini%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

            Florida Star v. B. J. F.

            Image
            Florida Star v. B. J. F. From Wikipedia, the free encyclopedia Jump to navigation Jump to search United States Supreme Court case Florida Star v. B. J. F. Supreme Court of the United States Argued March 21, 1989 Decided June 21, 1989 Full case name The Florida Star v. B. J. F. Citations 491 U.S. 524 ( more ) 109 S. Ct. 2603; 105 L. Ed. 2d 443; 1989 U.S. LEXIS 3120; 57 U.S.L.W. 4816; 16 Media L. Rep. 1801 Prior history The Florida Star v. B.J.F., 530 So.2d 286 (1988) Supreme Court of Florida; Florida Star v. B.J.F., 499 So.2d 883 (1986) Fla. Dist. Court of Appeals Holding Florida Stat. § 794.03 is unconstitutional to the extent it makes the truthful reporting of information that was a matter of public record unlawful, as it violates the First Amendment. Court membership Chief Justice William Rehnquist Associate Justices William J. Brennan Jr.  · Byron White Thurgood Marshall  · Harry Blac
            Read more

            Error while running script in elastic search , gateway timeout

            Image
            0 while running script in elastic search, I got 504 Gateway timeout error. { "query": { "bool": { "filter": { "script": { "script": " doc['creted_date'].date.getMonthOfYear() == 12 " } } } }, "aggs": { "test": { "date_histogram": { "field": "creted_date", "interval": "month", "format": "MMM" }, "aggs": { "cost": { "sum": { "field": "cost" } } }
            Read more

            Adding quotations to stringified JSON object values

            Image
            0 My stringified object data doesn't include quotation marks around object values, which errors when attempting JSON.parse() : '{ "affiliation": CORPORATE, "userId": 75c35d1c-5d12-4485-8fa8-b2f1551a3e6e }' I need the string to be: '{ "affiliation": "CORPORATE", "userId": "75c35d1c-5d12-4485-8fa8-b2f1551a3e6e" }' I'm using this regex to add quotes to the object keys: var newStr = str.replace(/(['"])?([a-z0-9A-Z_]+)(['"])?:/g, '"$2": '); For instance: '{ affiliation: CORPORATE }' to '{ "affiliation": CORPORATE }' There are only string values in my data, so I don't need to check value types. How can I alter my regex expression to add quotations to
            Read more