## 16 Reputation

12 years, 59 days

## Extract the argument of a trigonometric ...

Regards,

I have a very large equation which has an arctan(x,y). I need to be able to extract the arguments x,y and assign them in some variables.

I have tried the solution given here.

Unfortunately, that solution only works for constants, not equations.

For example, if I use the proc given in there with arctan(10,11) it works. But if I use something like arctan...

## Can Maple solve a non-linear recurrency ...

Greetings,

I want to solve the non linear recurrency system:

x[1](k*T+T) = x[1](k*T)+2*u[1]*psi*cos(alpha); x[2](k*T+T) = x[2](k*T)+2*u[1]*psi*sin(alpha); theta[0](k*T+T) = theta[0](k*T)+T*u[2];

with:

psi := piecewise(u2 <> 0, sin((1/2)*T*u[2])/u[2], (1/2)*T); alpha := theta[0]+(1/2)*T*u[2];

and u1 and u2 some functions of x1(kT) and x2(kT).

I tried to use the rsolve command but didn't work.

Can you help me, please? Is there some way to solve this?...

## Solve a weird Differential Equation...

Maple

Greetings,

I am triying to plot the solution of the next differential equation:

-diff(x*(diff(u(x), x)), x)+u(x) = 0

With the ics:

u(0) = 1

x*D(u)(x)=0 when x=1.

How can I do that?

I tried to get the solution using numeric methods, but I have the message:

Error, (in dsolve/numeric/bvp) system is singular at left endpoint, use midpoint method instead

I tried to use midpoint method and I still get an error message.

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