Class of fractal curves derived from recursion on the base-2 representation of the integers

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Consider the recurrence




$displaystyle
T(n) = begincases
1 &textif n = 0 \
0 &textif n = 1 \
T(lfloor n/2rfloor) + T(n bmod 2) &textotherwise
endcases
$




If you plot the value of this recurrence at the nonnegative integers, you get a fractal curve:



enter image description here



(The red line is $lfloorlog_2 nrfloor$; if you set $T(1)=1$ instead of $T(1)=0$, the recurrence degenerates to that function.)



Does this fractal have a name? Is it a member of a more general class of curves?







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    up vote
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    down vote

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    1












    Consider the recurrence




    $displaystyle
    T(n) = begincases
    1 &textif n = 0 \
    0 &textif n = 1 \
    T(lfloor n/2rfloor) + T(n bmod 2) &textotherwise
    endcases
    $




    If you plot the value of this recurrence at the nonnegative integers, you get a fractal curve:



    enter image description here



    (The red line is $lfloorlog_2 nrfloor$; if you set $T(1)=1$ instead of $T(1)=0$, the recurrence degenerates to that function.)



    Does this fractal have a name? Is it a member of a more general class of curves?







    share|cite|improve this question





















      up vote
      2
      down vote

      favorite
      1









      up vote
      2
      down vote

      favorite
      1






      1





      Consider the recurrence




      $displaystyle
      T(n) = begincases
      1 &textif n = 0 \
      0 &textif n = 1 \
      T(lfloor n/2rfloor) + T(n bmod 2) &textotherwise
      endcases
      $




      If you plot the value of this recurrence at the nonnegative integers, you get a fractal curve:



      enter image description here



      (The red line is $lfloorlog_2 nrfloor$; if you set $T(1)=1$ instead of $T(1)=0$, the recurrence degenerates to that function.)



      Does this fractal have a name? Is it a member of a more general class of curves?







      share|cite|improve this question











      Consider the recurrence




      $displaystyle
      T(n) = begincases
      1 &textif n = 0 \
      0 &textif n = 1 \
      T(lfloor n/2rfloor) + T(n bmod 2) &textotherwise
      endcases
      $




      If you plot the value of this recurrence at the nonnegative integers, you get a fractal curve:



      enter image description here



      (The red line is $lfloorlog_2 nrfloor$; if you set $T(1)=1$ instead of $T(1)=0$, the recurrence degenerates to that function.)



      Does this fractal have a name? Is it a member of a more general class of curves?









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      share|cite|improve this question




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      asked Jul 22 at 17:13









      zwol

      266111




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          I'm not sure that "fractal" is the correct term for this curve, in spite of the seeming self-similarity. If we plot your curve over the interval $[0,2^m]$ for several choices of $m$, we find that the lengths are $2^m+1-2$:



          enter image description here



          As the curves roughly double in length with each step, we'd expect a dimension of 1.



          In the context of fractal geometry, it might make more sense to scale these curves so that each lies over the unit interval. If we plot them in correct aspect ratio, we see a picture that looks like so:



          enter image description here



          Note that the limiting object is just the unit interval; the dimension is again 1.






          share|cite|improve this answer





















          • You're considering the entire domain of the recurrence, but isn't it more interesting if we consider intervals [2^n, 2^(n+1) - 1] for successive values of n as successive iterations of the fractal generator?
            – zwol
            Jul 24 at 13:12










          • Hmm... I. think I'm considering the limiting object when we grab pieces over the intervals $[0,2^n]$. I don't think changing the intervals to $[2^n,2^n+1-1]$ would make a huge difference. In any event, if we want to apply the ideas of fractal geometry, then it's natural to consider a limit of some sort.
            – Mark McClure
            Jul 24 at 13:48










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          up vote
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          I'm not sure that "fractal" is the correct term for this curve, in spite of the seeming self-similarity. If we plot your curve over the interval $[0,2^m]$ for several choices of $m$, we find that the lengths are $2^m+1-2$:



          enter image description here



          As the curves roughly double in length with each step, we'd expect a dimension of 1.



          In the context of fractal geometry, it might make more sense to scale these curves so that each lies over the unit interval. If we plot them in correct aspect ratio, we see a picture that looks like so:



          enter image description here



          Note that the limiting object is just the unit interval; the dimension is again 1.






          share|cite|improve this answer





















          • You're considering the entire domain of the recurrence, but isn't it more interesting if we consider intervals [2^n, 2^(n+1) - 1] for successive values of n as successive iterations of the fractal generator?
            – zwol
            Jul 24 at 13:12










          • Hmm... I. think I'm considering the limiting object when we grab pieces over the intervals $[0,2^n]$. I don't think changing the intervals to $[2^n,2^n+1-1]$ would make a huge difference. In any event, if we want to apply the ideas of fractal geometry, then it's natural to consider a limit of some sort.
            – Mark McClure
            Jul 24 at 13:48














          up vote
          2
          down vote













          I'm not sure that "fractal" is the correct term for this curve, in spite of the seeming self-similarity. If we plot your curve over the interval $[0,2^m]$ for several choices of $m$, we find that the lengths are $2^m+1-2$:



          enter image description here



          As the curves roughly double in length with each step, we'd expect a dimension of 1.



          In the context of fractal geometry, it might make more sense to scale these curves so that each lies over the unit interval. If we plot them in correct aspect ratio, we see a picture that looks like so:



          enter image description here



          Note that the limiting object is just the unit interval; the dimension is again 1.






          share|cite|improve this answer





















          • You're considering the entire domain of the recurrence, but isn't it more interesting if we consider intervals [2^n, 2^(n+1) - 1] for successive values of n as successive iterations of the fractal generator?
            – zwol
            Jul 24 at 13:12










          • Hmm... I. think I'm considering the limiting object when we grab pieces over the intervals $[0,2^n]$. I don't think changing the intervals to $[2^n,2^n+1-1]$ would make a huge difference. In any event, if we want to apply the ideas of fractal geometry, then it's natural to consider a limit of some sort.
            – Mark McClure
            Jul 24 at 13:48












          up vote
          2
          down vote










          up vote
          2
          down vote









          I'm not sure that "fractal" is the correct term for this curve, in spite of the seeming self-similarity. If we plot your curve over the interval $[0,2^m]$ for several choices of $m$, we find that the lengths are $2^m+1-2$:



          enter image description here



          As the curves roughly double in length with each step, we'd expect a dimension of 1.



          In the context of fractal geometry, it might make more sense to scale these curves so that each lies over the unit interval. If we plot them in correct aspect ratio, we see a picture that looks like so:



          enter image description here



          Note that the limiting object is just the unit interval; the dimension is again 1.






          share|cite|improve this answer













          I'm not sure that "fractal" is the correct term for this curve, in spite of the seeming self-similarity. If we plot your curve over the interval $[0,2^m]$ for several choices of $m$, we find that the lengths are $2^m+1-2$:



          enter image description here



          As the curves roughly double in length with each step, we'd expect a dimension of 1.



          In the context of fractal geometry, it might make more sense to scale these curves so that each lies over the unit interval. If we plot them in correct aspect ratio, we see a picture that looks like so:



          enter image description here



          Note that the limiting object is just the unit interval; the dimension is again 1.







          share|cite|improve this answer













          share|cite|improve this answer



          share|cite|improve this answer











          answered Jul 23 at 16:13









          Mark McClure

          22.5k34069




          22.5k34069











          • You're considering the entire domain of the recurrence, but isn't it more interesting if we consider intervals [2^n, 2^(n+1) - 1] for successive values of n as successive iterations of the fractal generator?
            – zwol
            Jul 24 at 13:12










          • Hmm... I. think I'm considering the limiting object when we grab pieces over the intervals $[0,2^n]$. I don't think changing the intervals to $[2^n,2^n+1-1]$ would make a huge difference. In any event, if we want to apply the ideas of fractal geometry, then it's natural to consider a limit of some sort.
            – Mark McClure
            Jul 24 at 13:48
















          • You're considering the entire domain of the recurrence, but isn't it more interesting if we consider intervals [2^n, 2^(n+1) - 1] for successive values of n as successive iterations of the fractal generator?
            – zwol
            Jul 24 at 13:12










          • Hmm... I. think I'm considering the limiting object when we grab pieces over the intervals $[0,2^n]$. I don't think changing the intervals to $[2^n,2^n+1-1]$ would make a huge difference. In any event, if we want to apply the ideas of fractal geometry, then it's natural to consider a limit of some sort.
            – Mark McClure
            Jul 24 at 13:48















          You're considering the entire domain of the recurrence, but isn't it more interesting if we consider intervals [2^n, 2^(n+1) - 1] for successive values of n as successive iterations of the fractal generator?
          – zwol
          Jul 24 at 13:12




          You're considering the entire domain of the recurrence, but isn't it more interesting if we consider intervals [2^n, 2^(n+1) - 1] for successive values of n as successive iterations of the fractal generator?
          – zwol
          Jul 24 at 13:12












          Hmm... I. think I'm considering the limiting object when we grab pieces over the intervals $[0,2^n]$. I don't think changing the intervals to $[2^n,2^n+1-1]$ would make a huge difference. In any event, if we want to apply the ideas of fractal geometry, then it's natural to consider a limit of some sort.
          – Mark McClure
          Jul 24 at 13:48




          Hmm... I. think I'm considering the limiting object when we grab pieces over the intervals $[0,2^n]$. I don't think changing the intervals to $[2^n,2^n+1-1]$ would make a huge difference. In any event, if we want to apply the ideas of fractal geometry, then it's natural to consider a limit of some sort.
          – Mark McClure
          Jul 24 at 13:48












           

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