How to definine a function, when it contains the integral of the function itself?











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My question is basically if it is possible to define the following function. I tried in GeoGebra which solely says it is a circular definition, which I understand, however I do strongly believe that there most be one way or another ot calculate this. It is for a model of how the in and outflow of the Mediterranean behave - I a very thankful for any help!



$V(t)=int{sqrt{sin{t}-V(t)}dt}$



(full equation: $V(t)_{c}=A_{cs}int{sqrt{2g(a sin{(t)}+c-frac{V(t)_{c}+V_{M}}{A_{M}})}dt}$



Where this is basically water flowing from one bucket to another and back when one of which's height changes sinusoidally and the other in reaction to the first one.)



I am sorry for the most probably very fundamental nature of the question, however I couldn't find anything related to that in the forum.



Thanks for any answers in advance!










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  • What you have there is a specific integral equation, which is, more-or-less, a differential equation in reverse. There are techniques for solving such equations, though it might be helpful to know where you encountered this.
    – Xander Henderson
    yesterday










  • Thank you very much for your quick response! It was about a simple approach in tackling the tides in the Mediterranean. I left out all the constants, but it comes down to the fact that the speed of the flow is dependent on the difference in height and hence on how much water flowed up to a certain point in time.
    – xyaang
    yesterday










  • If you derivate your equation, you find $frac{dV}{dt}=sqrt{sin t-V}$ which is a non-circular differential equation for $V$. But a non-linear one, so good luck with that
    – thedude
    yesterday















up vote
2
down vote

favorite












My question is basically if it is possible to define the following function. I tried in GeoGebra which solely says it is a circular definition, which I understand, however I do strongly believe that there most be one way or another ot calculate this. It is for a model of how the in and outflow of the Mediterranean behave - I a very thankful for any help!



$V(t)=int{sqrt{sin{t}-V(t)}dt}$



(full equation: $V(t)_{c}=A_{cs}int{sqrt{2g(a sin{(t)}+c-frac{V(t)_{c}+V_{M}}{A_{M}})}dt}$



Where this is basically water flowing from one bucket to another and back when one of which's height changes sinusoidally and the other in reaction to the first one.)



I am sorry for the most probably very fundamental nature of the question, however I couldn't find anything related to that in the forum.



Thanks for any answers in advance!










share|cite|improve this question









New contributor




xyaang is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.




















  • What you have there is a specific integral equation, which is, more-or-less, a differential equation in reverse. There are techniques for solving such equations, though it might be helpful to know where you encountered this.
    – Xander Henderson
    yesterday










  • Thank you very much for your quick response! It was about a simple approach in tackling the tides in the Mediterranean. I left out all the constants, but it comes down to the fact that the speed of the flow is dependent on the difference in height and hence on how much water flowed up to a certain point in time.
    – xyaang
    yesterday










  • If you derivate your equation, you find $frac{dV}{dt}=sqrt{sin t-V}$ which is a non-circular differential equation for $V$. But a non-linear one, so good luck with that
    – thedude
    yesterday













up vote
2
down vote

favorite









up vote
2
down vote

favorite











My question is basically if it is possible to define the following function. I tried in GeoGebra which solely says it is a circular definition, which I understand, however I do strongly believe that there most be one way or another ot calculate this. It is for a model of how the in and outflow of the Mediterranean behave - I a very thankful for any help!



$V(t)=int{sqrt{sin{t}-V(t)}dt}$



(full equation: $V(t)_{c}=A_{cs}int{sqrt{2g(a sin{(t)}+c-frac{V(t)_{c}+V_{M}}{A_{M}})}dt}$



Where this is basically water flowing from one bucket to another and back when one of which's height changes sinusoidally and the other in reaction to the first one.)



I am sorry for the most probably very fundamental nature of the question, however I couldn't find anything related to that in the forum.



Thanks for any answers in advance!










share|cite|improve this question









New contributor




xyaang is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











My question is basically if it is possible to define the following function. I tried in GeoGebra which solely says it is a circular definition, which I understand, however I do strongly believe that there most be one way or another ot calculate this. It is for a model of how the in and outflow of the Mediterranean behave - I a very thankful for any help!



$V(t)=int{sqrt{sin{t}-V(t)}dt}$



(full equation: $V(t)_{c}=A_{cs}int{sqrt{2g(a sin{(t)}+c-frac{V(t)_{c}+V_{M}}{A_{M}})}dt}$



Where this is basically water flowing from one bucket to another and back when one of which's height changes sinusoidally and the other in reaction to the first one.)



I am sorry for the most probably very fundamental nature of the question, however I couldn't find anything related to that in the forum.



Thanks for any answers in advance!







integration






share|cite|improve this question









New contributor




xyaang is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|cite|improve this question









New contributor




xyaang is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









share|cite|improve this question




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edited yesterday





















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asked 2 days ago









xyaang

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133




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xyaang is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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New contributor





xyaang is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






xyaang is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.












  • What you have there is a specific integral equation, which is, more-or-less, a differential equation in reverse. There are techniques for solving such equations, though it might be helpful to know where you encountered this.
    – Xander Henderson
    yesterday










  • Thank you very much for your quick response! It was about a simple approach in tackling the tides in the Mediterranean. I left out all the constants, but it comes down to the fact that the speed of the flow is dependent on the difference in height and hence on how much water flowed up to a certain point in time.
    – xyaang
    yesterday










  • If you derivate your equation, you find $frac{dV}{dt}=sqrt{sin t-V}$ which is a non-circular differential equation for $V$. But a non-linear one, so good luck with that
    – thedude
    yesterday


















  • What you have there is a specific integral equation, which is, more-or-less, a differential equation in reverse. There are techniques for solving such equations, though it might be helpful to know where you encountered this.
    – Xander Henderson
    yesterday










  • Thank you very much for your quick response! It was about a simple approach in tackling the tides in the Mediterranean. I left out all the constants, but it comes down to the fact that the speed of the flow is dependent on the difference in height and hence on how much water flowed up to a certain point in time.
    – xyaang
    yesterday










  • If you derivate your equation, you find $frac{dV}{dt}=sqrt{sin t-V}$ which is a non-circular differential equation for $V$. But a non-linear one, so good luck with that
    – thedude
    yesterday
















What you have there is a specific integral equation, which is, more-or-less, a differential equation in reverse. There are techniques for solving such equations, though it might be helpful to know where you encountered this.
– Xander Henderson
yesterday




What you have there is a specific integral equation, which is, more-or-less, a differential equation in reverse. There are techniques for solving such equations, though it might be helpful to know where you encountered this.
– Xander Henderson
yesterday












Thank you very much for your quick response! It was about a simple approach in tackling the tides in the Mediterranean. I left out all the constants, but it comes down to the fact that the speed of the flow is dependent on the difference in height and hence on how much water flowed up to a certain point in time.
– xyaang
yesterday




Thank you very much for your quick response! It was about a simple approach in tackling the tides in the Mediterranean. I left out all the constants, but it comes down to the fact that the speed of the flow is dependent on the difference in height and hence on how much water flowed up to a certain point in time.
– xyaang
yesterday












If you derivate your equation, you find $frac{dV}{dt}=sqrt{sin t-V}$ which is a non-circular differential equation for $V$. But a non-linear one, so good luck with that
– thedude
yesterday




If you derivate your equation, you find $frac{dV}{dt}=sqrt{sin t-V}$ which is a non-circular differential equation for $V$. But a non-linear one, so good luck with that
– thedude
yesterday










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What you write is a integral equation, which can be easily be turned to an ordinary differential equation by differentiation.



$$V'(x)=sqrt{sin t-V(t)}$$ or



$$V'^2(t)+V(t)=sin t.$$



(We have many more techniques for solving ODEs than integral equations.)



Unfortunately, this one resists to resolution.






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    1 Answer
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    active

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    1 Answer
    1






    active

    oldest

    votes









    active

    oldest

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    active

    oldest

    votes








    up vote
    1
    down vote



    accepted










    What you write is a integral equation, which can be easily be turned to an ordinary differential equation by differentiation.



    $$V'(x)=sqrt{sin t-V(t)}$$ or



    $$V'^2(t)+V(t)=sin t.$$



    (We have many more techniques for solving ODEs than integral equations.)



    Unfortunately, this one resists to resolution.






    share|cite|improve this answer

























      up vote
      1
      down vote



      accepted










      What you write is a integral equation, which can be easily be turned to an ordinary differential equation by differentiation.



      $$V'(x)=sqrt{sin t-V(t)}$$ or



      $$V'^2(t)+V(t)=sin t.$$



      (We have many more techniques for solving ODEs than integral equations.)



      Unfortunately, this one resists to resolution.






      share|cite|improve this answer























        up vote
        1
        down vote



        accepted







        up vote
        1
        down vote



        accepted






        What you write is a integral equation, which can be easily be turned to an ordinary differential equation by differentiation.



        $$V'(x)=sqrt{sin t-V(t)}$$ or



        $$V'^2(t)+V(t)=sin t.$$



        (We have many more techniques for solving ODEs than integral equations.)



        Unfortunately, this one resists to resolution.






        share|cite|improve this answer












        What you write is a integral equation, which can be easily be turned to an ordinary differential equation by differentiation.



        $$V'(x)=sqrt{sin t-V(t)}$$ or



        $$V'^2(t)+V(t)=sin t.$$



        (We have many more techniques for solving ODEs than integral equations.)



        Unfortunately, this one resists to resolution.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered yesterday









        Yves Daoust

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