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Re: Help on Project

  • To: mathgroup at
  • Subject: [mg5069] Re: [mg5056] Help on Project
  • From: stoev at
  • Date: Fri, 25 Oct 1996 22:48:12 -0400
  • Sender: owner-wri-mathgroup at

Right now I do not have access to Mathematica, but as I remember 
InterpolatingFunction[] may help you. You have also Interpolate[]. Then you 
have two possibilities:
First: Traditional solution. 
You interpolate acceleration and you Integrate[] twice with respect to 
your initial conditions (position and speed) and you get actual position 
and spped in every time moment.
Second: Not so traditional solution.
Interpolate[] uses some kind of spline interpolaton. That's why you can
put your acceleration data in the interpolation of position as second
derivatives of the position and also the moments in the time for which you
have this accelerations. You must also put your initial conditions for
some moment of time as initiol position and initial speed (let's say for
t=0). Then spine interpolation does all the rest. You must be able to plot
the result function. 
In both cases you must be prepared to have reletively big error in the 
result, because you integrate approximated data, but that's the data you 
have only. Maybe one of these algorithms is better for you, but this you 
must select by yourself. Intuitively I yould prefere the second solution, 
because the splines were invented (I think) for problems like this.
In both cases you must see the syntaxis of functions you will use in the 
manual or in Mathematica.
 For ploting I can't help you in this moment. 

Julian Stoev

On Wed, 23 Oct 1996, Keith Salmon wrote:

> I am new to Mathematica and need help with a project.  I have acceleration
> data from the flight path of a missile that I would like to integrate to
> get velocity and position relative to the launch point of the missile.  The
> acceleration information is referenced to a body axis which translates and
> rotates with respect to the launch (inertial) axis.  I want to be able to
> plot in 2-D and 3-D the flight path to impact of the target and  determine
> impact angle and velocity.  As I mentioned, I am not familiar with all the
> inner workings of Mathematica and would appreciate any help building a
> front end to the acceleration data that would allow future data to be
> analyzed in the same fashion.  Please email constructive suggestions to
> salmonke at   Any and all help is appreciated.
> Keith Salmon

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