Issues with notation of Ito Integral

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How should I interoperate $X_t_j$, does usually when I previously have seen double subscript it refer to having multidimensions.



In this case it looks like we are splitting up t into sections.
In other words we could have that t goes from 0 to T, in steps of t.



however, is the second subscript referring to splitting up [0,t] into furter increments?



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  • 1




    $X_t$ is a (random) function of $t.$ $X_t_i$ is that function evaluated at $t=t_i.$ The $t_i$ are an evenly spaced sequence of sample points in the interval... compare to the evaluation points for a Riemann integral or something like that.
    – spaceisdarkgreen
    Jul 16 at 23:51










  • @spaceisdarkgreen So I could consider it being the ith element of $X_t$ ?
    – ALEXANDER
    Jul 17 at 0:49






  • 1




    No... that's not what I said.
    – spaceisdarkgreen
    Jul 17 at 1:06










  • @spaceisdarkgreen Would you be able to write more in depth answer to the solution provided to this answer, where he uses the term ith element.: math.stackexchange.com/questions/2710012/…
    – ALEXANDER
    Jul 17 at 2:06






  • 1




    In this example in this question, the $i$ refers to the $i$-th time step in a discretization of the time axis. In other words we're taking a function defined on some interval, but only looking at a finite number of points (and then taking a limit as we go to finer and finer spaced points in order to recover information about the continuous time function... as we do in, say, the Riemann or Stieljes integral)
    – spaceisdarkgreen
    Jul 17 at 2:55















up vote
0
down vote

favorite












How should I interoperate $X_t_j$, does usually when I previously have seen double subscript it refer to having multidimensions.



In this case it looks like we are splitting up t into sections.
In other words we could have that t goes from 0 to T, in steps of t.



however, is the second subscript referring to splitting up [0,t] into furter increments?



enter image description here







share|cite|improve this question















  • 1




    $X_t$ is a (random) function of $t.$ $X_t_i$ is that function evaluated at $t=t_i.$ The $t_i$ are an evenly spaced sequence of sample points in the interval... compare to the evaluation points for a Riemann integral or something like that.
    – spaceisdarkgreen
    Jul 16 at 23:51










  • @spaceisdarkgreen So I could consider it being the ith element of $X_t$ ?
    – ALEXANDER
    Jul 17 at 0:49






  • 1




    No... that's not what I said.
    – spaceisdarkgreen
    Jul 17 at 1:06










  • @spaceisdarkgreen Would you be able to write more in depth answer to the solution provided to this answer, where he uses the term ith element.: math.stackexchange.com/questions/2710012/…
    – ALEXANDER
    Jul 17 at 2:06






  • 1




    In this example in this question, the $i$ refers to the $i$-th time step in a discretization of the time axis. In other words we're taking a function defined on some interval, but only looking at a finite number of points (and then taking a limit as we go to finer and finer spaced points in order to recover information about the continuous time function... as we do in, say, the Riemann or Stieljes integral)
    – spaceisdarkgreen
    Jul 17 at 2:55













up vote
0
down vote

favorite









up vote
0
down vote

favorite











How should I interoperate $X_t_j$, does usually when I previously have seen double subscript it refer to having multidimensions.



In this case it looks like we are splitting up t into sections.
In other words we could have that t goes from 0 to T, in steps of t.



however, is the second subscript referring to splitting up [0,t] into furter increments?



enter image description here







share|cite|improve this question











How should I interoperate $X_t_j$, does usually when I previously have seen double subscript it refer to having multidimensions.



In this case it looks like we are splitting up t into sections.
In other words we could have that t goes from 0 to T, in steps of t.



however, is the second subscript referring to splitting up [0,t] into furter increments?



enter image description here









share|cite|improve this question










share|cite|improve this question




share|cite|improve this question









asked Jul 16 at 23:12









ALEXANDER

850818




850818







  • 1




    $X_t$ is a (random) function of $t.$ $X_t_i$ is that function evaluated at $t=t_i.$ The $t_i$ are an evenly spaced sequence of sample points in the interval... compare to the evaluation points for a Riemann integral or something like that.
    – spaceisdarkgreen
    Jul 16 at 23:51










  • @spaceisdarkgreen So I could consider it being the ith element of $X_t$ ?
    – ALEXANDER
    Jul 17 at 0:49






  • 1




    No... that's not what I said.
    – spaceisdarkgreen
    Jul 17 at 1:06










  • @spaceisdarkgreen Would you be able to write more in depth answer to the solution provided to this answer, where he uses the term ith element.: math.stackexchange.com/questions/2710012/…
    – ALEXANDER
    Jul 17 at 2:06






  • 1




    In this example in this question, the $i$ refers to the $i$-th time step in a discretization of the time axis. In other words we're taking a function defined on some interval, but only looking at a finite number of points (and then taking a limit as we go to finer and finer spaced points in order to recover information about the continuous time function... as we do in, say, the Riemann or Stieljes integral)
    – spaceisdarkgreen
    Jul 17 at 2:55













  • 1




    $X_t$ is a (random) function of $t.$ $X_t_i$ is that function evaluated at $t=t_i.$ The $t_i$ are an evenly spaced sequence of sample points in the interval... compare to the evaluation points for a Riemann integral or something like that.
    – spaceisdarkgreen
    Jul 16 at 23:51










  • @spaceisdarkgreen So I could consider it being the ith element of $X_t$ ?
    – ALEXANDER
    Jul 17 at 0:49






  • 1




    No... that's not what I said.
    – spaceisdarkgreen
    Jul 17 at 1:06










  • @spaceisdarkgreen Would you be able to write more in depth answer to the solution provided to this answer, where he uses the term ith element.: math.stackexchange.com/questions/2710012/…
    – ALEXANDER
    Jul 17 at 2:06






  • 1




    In this example in this question, the $i$ refers to the $i$-th time step in a discretization of the time axis. In other words we're taking a function defined on some interval, but only looking at a finite number of points (and then taking a limit as we go to finer and finer spaced points in order to recover information about the continuous time function... as we do in, say, the Riemann or Stieljes integral)
    – spaceisdarkgreen
    Jul 17 at 2:55








1




1




$X_t$ is a (random) function of $t.$ $X_t_i$ is that function evaluated at $t=t_i.$ The $t_i$ are an evenly spaced sequence of sample points in the interval... compare to the evaluation points for a Riemann integral or something like that.
– spaceisdarkgreen
Jul 16 at 23:51




$X_t$ is a (random) function of $t.$ $X_t_i$ is that function evaluated at $t=t_i.$ The $t_i$ are an evenly spaced sequence of sample points in the interval... compare to the evaluation points for a Riemann integral or something like that.
– spaceisdarkgreen
Jul 16 at 23:51












@spaceisdarkgreen So I could consider it being the ith element of $X_t$ ?
– ALEXANDER
Jul 17 at 0:49




@spaceisdarkgreen So I could consider it being the ith element of $X_t$ ?
– ALEXANDER
Jul 17 at 0:49




1




1




No... that's not what I said.
– spaceisdarkgreen
Jul 17 at 1:06




No... that's not what I said.
– spaceisdarkgreen
Jul 17 at 1:06












@spaceisdarkgreen Would you be able to write more in depth answer to the solution provided to this answer, where he uses the term ith element.: math.stackexchange.com/questions/2710012/…
– ALEXANDER
Jul 17 at 2:06




@spaceisdarkgreen Would you be able to write more in depth answer to the solution provided to this answer, where he uses the term ith element.: math.stackexchange.com/questions/2710012/…
– ALEXANDER
Jul 17 at 2:06




1




1




In this example in this question, the $i$ refers to the $i$-th time step in a discretization of the time axis. In other words we're taking a function defined on some interval, but only looking at a finite number of points (and then taking a limit as we go to finer and finer spaced points in order to recover information about the continuous time function... as we do in, say, the Riemann or Stieljes integral)
– spaceisdarkgreen
Jul 17 at 2:55





In this example in this question, the $i$ refers to the $i$-th time step in a discretization of the time axis. In other words we're taking a function defined on some interval, but only looking at a finite number of points (and then taking a limit as we go to finer and finer spaced points in order to recover information about the continuous time function... as we do in, say, the Riemann or Stieljes integral)
– spaceisdarkgreen
Jul 17 at 2:55
















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