## 35 Reputation

12 years, 145 days

## It works but no arrows...

It works even if I don't understand why do I need an evalc since I am asking for the real part and the imaginary part (so it is a real number).

Now, I don't get the arrows. Is it normal even if it is declared in the plot function?

## It works but no arrows...

It works even if I don't understand why do I need an evalc since I am asking for the real part and the imaginary part (so it is a real number).

Now, I don't get the arrows. Is it normal even if it is declared in the plot function?

## Ok one step to the answer may be...

There is a multipication sign missing in f1 and g1, here is the corrected code:

restart;with(DEtools), with(plots), with(linalg):

z:=exp(I*((t/(2*Pi))+(2*Pi*j/3)));

f1:=Re((I/(2*Pi))*((1/(subs(j=1,z)-(x(t)+I*y(t))))+(1/(subs(j=2,z)-(x(t)+I*y(t))))+(1/(subs(j=3,z)-(x(t)+I*y(t))))));

g1:=-1*Im((I/(2*Pi))*((1/(subs(j=1,z)-(x(t)+I*y(t))))+(1/(subs(j=2,z)-(x(t)+I*y(t))))+(1/(subs(j=3,z)-(x(t)+I*y(t))))));

sys1:=[diff(x(t),t)=f1,diff(y(t),t)=g1]:

F := DEplot(sys1, [x(t), y(t)], t = -20 .. 10, x = -2 .. 2, y = -2 .. 2, [[x(0) =0, y(0) = 0]],linecolor = blue, thickness = 2, stepsize = .1, arrows = medium, color = red);

Now there is a solution but also another error:

`Warning, plot may be incomplete, the following errors(s) were issued:   solution becomes complex valued`
` `
`Any advice on how can I solve that?`

## Ok...

Thank you very much, it is exactly what I needed.

Is it possible to draw the flow vectors in all the plane as well? I can do it only on the trajectory itself but not for other points.

## Ok...

Thank you very much, it is exactly what I needed.

Is it possible to draw the flow vectors in all the plane as well? I can do it only on the trajectory itself but not for other points.

## Numerical?...

Thank you very much for all these details.

What do you mean by numerical noise?

All what I have is wiener processes that I defined with the function WienerProcess. Is that what you consider numerical?

## Numerical?...

Thank you very much for all these details.

What do you mean by numerical noise?

All what I have is wiener processes that I defined with the function WienerProcess. Is that what you consider numerical?

## so do you mean that if I ask for U(1.001...

so do you mean that if I ask for U(1.001) he can't do it?

## so do you mean that if I ask for U(1.001...

so do you mean that if I ask for U(1.001) he can't do it?

## :D Just realised that I wrote that 0.001...

:D Just realised that I wrote that 0.001 is integer.

But anyway, It doesn't have to be an integer in my application.

## :D Just realised that I wrote that 0.001...

:D Just realised that I wrote that 0.001 is integer.

But anyway, It doesn't have to be an integer in my application.

## Yes d is an integer (0.001 for me). As ...

Yes d is an integer (0.001 for me).

As I explained in the beginning, it is part of a filtering algorithm. I have a stochastic noisy system and I want to find some probability density.

Wikipedia explains it better than me : http://en.wikipedia.org/wiki/Recursive_Bayesian_estimation

So if I want to evaluate this integral, will the Upper case and the quotation cause problems?

## Yes d is an integer (0.001 for me). As ...

Yes d is an integer (0.001 for me).

As I explained in the beginning, it is part of a filtering algorithm. I have a stochastic noisy system and I want to find some probability density.

Wikipedia explains it better than me : http://en.wikipedia.org/wiki/Recursive_Bayesian_estimation

So if I want to evaluate this integral, will the Upper case and the quotation cause problems?

## here is the explanation...

d is say the Δt (the time step)

mu is the expected value of U(k) given U(k-d):

`mu1:=proc(k)> if k=0 then> Vector[column]([[X(0)[1]],[X(0)[2]],[X(0)[3]],[X(0)[4]],[H(1,1,0)],[H(2,1,0)],[H(1,2,0)],[H(2,2,0)],[H(1,3,0)],[H(2,3,0)],[H(1,4,0)],[H(2,4,0)]]);> else> U(k-d)+d*D1(k-d).U(k-d);> fi;> end proc:`
`Then, "integrate p1(k)*p0(k-1) over IR^12, where the variables are w1 ... w12" that is exactly what I want.`
`Could you explain what the uppercase and the quotation mark stand for?`
` `
`Thank you for your answer.`

## here is the explanation...

d is say the Δt (the time step)

mu is the expected value of U(k) given U(k-d):

`mu1:=proc(k)> if k=0 then> Vector[column]([[X(0)[1]],[X(0)[2]],[X(0)[3]],[X(0)[4]],[H(1,1,0)],[H(2,1,0)],[H(1,2,0)],[H(2,2,0)],[H(1,3,0)],[H(2,3,0)],[H(1,4,0)],[H(2,4,0)]]);> else> U(k-d)+d*D1(k-d).U(k-d);> fi;> end proc:`
`Then, "integrate p1(k)*p0(k-1) over IR^12, where the variables are w1 ... w12" that is exactly what I want.`
`Could you explain what the uppercase and the quotation mark stand for?`
` `
`Thank you for your answer.`
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