Getting only first component from vector/matrix output
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I'm using ode45 to solve a second-order IVP and want to use deval to evaluate the solution.
Since the equation was second-order, the solution vector has two components. I am wondering if there's an easy way to just get only the first component without having to assign deval's output to a temporary variable first?
I would've expected syntax like (deval(sol,x))(1) to work but it doesn't.
The same question applies not just to deval, but to any function which returns a vector/matrix.
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Walter Roberson
2011-4-1
subsref(deval(sol,x),struct('type','()','subs',1))
If you are doing this multiple times, then just use (e.g.,)
first = @(x) x(1);
first(deval(sol,x))
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Sean de Wolski
2011-4-1
0 个投票
No. MATLAB does not support cascading indexing (except for in structures; which wouldn't be applicable here).
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Positronized
2011-4-1
Sean de Wolski
2011-4-1
You can use Walter's function handle, that will do it in one line. The temporary variable will still have to be created; however, in addition to the creation of the function handle and the call to it. What's so bad about having to return a temp variable?
Positronized
2011-4-1
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2011-4-1
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