Trying to learn math :)

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awarded Popular Question
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comment Non affine control?
Thanks!, indeed I would like to tackle the case when f(x,t) is bounded but may be zero. Probably I can assume that f(x,t) is zero only on a set of measure zero... but I would be interested on not so restrictive cases, if they have been studied.
Jun
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asked Non affine control?
Jan
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accepted Use string to select a function and/or a variable (Julia)
Jan
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accepted eigenvalues weighted ring graph
Jan
27
comment eigenvalues weighted ring graph
Thanks. However, even for the weighted case, eigenvectors are still orthogonal. So, in some sense I would have expected that the "Fourier" description of eigenvectors still holds, while naturally the weights would then "only" affect the eigenvalues.
Jan
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revised eigenvalues weighted ring graph
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Jan
26
asked eigenvalues weighted ring graph
2018
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asked Use string to select a function and/or a variable (Julia)
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awarded Nice Question
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comment Drawing directions fields
@RicardoAcuna the U,V formulas in the program are exclusively for the arrows and are exactly equal to the equations of the vf (vector field) function. So, if you want to plot a similar picture, say for $(x',y')=(f_1(x,y),f_2(x,y))$ write $(U,V)=(f_1(X,Y),f_2(X,Y)$. Note that I use big $(X,Y)$ to denote the coordinates of the mesh. Then, you use $N$ to normalise the arrows, so that all of them have the same length. Therefore, it is important to note that the picture you get is for a normalised vector field in which only the direction is shown but not the velocity itself. Hope this helps.
Feb
26
comment Drawing directions fields
@RicardoAcuna U=1 because of the particular example. The part that follows #Vector field is exclusively to draw the arrows in accordance to the definition of #Vector field function. Of course changing vf(t,x) should be followed by an appropriate change of U,V
Feb
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accepted Sufficient conditions for global stability from linear stability.
Feb
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asked Sufficient conditions for global stability from linear stability.
Feb
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revised Transforming linear dynamical system to reduce magnitude of eigen values
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