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Unread 08-10-2013, 00:10
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Re: calculating position using follower wheels

Quote:
Originally Posted by Ether View Post
That matches my results out to the number of decimal places shown, except I'm getting a 6 instead of a 5 in the fourth decimal place of the Y value
I re-ran my script once for each of MATLAB's ODE solvers, adjusting the tolerances as necessary to get a reasonable solve time.

Every solver agreed through the fifth decimal place (for the Y value). The stiff solvers needed significantly larger error tolerances and took more steps; their predicted error was much higher.

The nonstiff solvers all agreed through the seventh decimal place.

The lowest predicted error was obtained through the ode113 solver, using a relative tolerance of 100 * epsilon and an absolute tolerance of 10^-12. According to my error estimate, all of the following digits are correct:

Spoiler for solution:
Position: (-3.73497544, -4.06852591)
Distance: 60.86682701


It was interesting going through all the solvers -- many of the stiff solvers had error estimates in excess of 10^-4. I guess this shows that the choice of solver really can have an effect on the error, and not just the solution time.
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