# Items tagged with conditioncondition Tagged Items Feed

### How do I find a condition on a characteristic equa...

March 12 2015
0 5

I have the following characteristic equation by use of maple. How do I find a condition on x, that will return real eigenvalues and complex eigenvalues?

### Error, (in dsolve/numeric/bvp) initial Newton iter...

January 12 2015
1 2

Dear All,

I am solving 6 ODE equations with boundary conditions using Runge kutta Felbergh 45 (Maple 12). then, i got this problem.. any suggestion??

Thank you :)

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 Error, (in dsolve/numeric/bvp) initial Newton iteration is not converging
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 Warning, unable to evaluate the function to numeric values in the region; see the plotting command's help page to ensure the calling sequence is correct
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### Can I plot3d with an inequality condition?...

December 14 2014
1 10

I would like to look at a 3d plot including an condition about the two variables of the plot

For this simple case, I only want to see the plot with the condition that x>0. Is that possible?

plot3d(x*y,[x,0,1],[y,0,1]);

### Computing eigenvalues with assumptions...

December 07 2014
1 6

I am trying to simplify the eigenvalues of a 2x2 matrix [[a,b],[c,d]] subject to the condition a,b,c, and d are integers such that a+b = c+d. Why do the following commands not achieve this?

with(LinearAlgebra):

A:=Matrix[[a,b],[c,d]]):

Eigenvalues(A) assuming a::integer,b::integer,c::integer,d::integer,a+b=d+c

How might I achieve what I need?

### periodic boundary conditions...

December 03 2014
0 6

Hello,

Since I was working in Matlab with Galerkin method which implies periodic boundary conditions I was wondering how to implement this in maple.

I tried this:

restart;

pde2 := diff(u(x, t), t)+3*(diff(u(x, t)^2, x))+diff(u(x, t),x\$3) = 0

IBC := {u(0, t) = u(2, t), u(x, 0) = sech(50*(x-1/2))^2+2*sech(30*(x-1))^2, (D[1](u))(0, t) = (D[1](u))(2, t), (D[2](u))(0, t) = (D[2](u))(2, t)}

pds := pdsolve(pde2, IBC, numeric, time = t, range = 0 .. 2)

But it's telling me:

Error, (in pdsolve/numeric/process_IBCs) initial/boundary conditions can only contain derivatives which are normal to the boundary, got (D[2](u))(0, t)

So what's wrong?

### Sytem of equation solution ...

November 21 2014
0 0

Dear all:

hello everybody;

I need your help to solve the system f(x,y)=0, and g(x,y)=0, such that there some parameter in the system, also all the parameter are positive and also our unkowns  x and y are also positive.

I try to write this code. I feel that under some condition we can have four solution or three or two. I need your help. Many thinks.

Systemsolve.mw

### Error, (in dsolve/numeric/bvp) initial Newton iter...

November 10 2014
0 8

i am solving 3 ODE with boundary condition.. with boundary condition

b.mw

Maple Worksheet - Error

Failed to load the worksheet /maplenet/convert/b.mw .

then i got this error

Error, (in dsolve/numeric/bvp) initial Newton iteration is not converging

i dont know where i need to change.. could you help me..

### Error, (in dsolve/numeric/bvp) initial Newton iter...

November 06 2014
0 2

i am solving 3 ODE question with boundary condition. when i running the programm i got this error.. any one could help me please.. :)

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 Error, (in dsolve/numeric/bvp) initial Newton iteration is not converging
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 Warning, unable to evaluate the functions to numeric values in the region; see the plotting command's help page to ensure the calling sequence is correct
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### differential equation system...

October 23 2014
0 4

With your help I have a solution to a system of three equations:

(parameters are calculated on the basis of the data (for different values) - one example below)
A1=0.00002072968491, A2=0, A3=0.001946449287, A4=0.01946449287

B1=, B2=0, B3=0.0004773383613, B4=0.00004773383613

C1=, C2=0, C3=, C4=0.00009087604510

eqa1: = A1 * (diff (Tg (x), x, x)) + A2 * (diff (Tg (x), x)) + (A3 + A4) * tan (x) + A3 * Tg (x) + A4 * Tw (x) = 0;

eqa2: = B1 * (diff (Tw (x), x, x)) + B2 * (diff (Tw (x), x)) + (B3 + B4) * Tw (x) + B3 * Tg (x) + B4 * tan (x) = 0;

eqa3: = C1 * (diff (Tz (x), x, x)) + (C3 + C4) * Tg (x) + C3 * tan (x) + C4 * Tw (x) = 0;

indets ({eqa1, eqa2, eqa3}) minus {x};

res: = Dsolve (eval ({eqa1, eqa2, eqa3}) union {boundary conditions ??}, numeric);

for k from 0 to 20 evalf (res (k), 4); from;

c1:= 0.524:

c2:=0.05:

m: = 0;

for m from 0 to 20 and

T (m): = c1 * rhs (op (6, res (m))) + c2 * rhs (op (2, res (m))) + (1-c1-c2) * rhs (op (4, res (m))); print (m, T (m)); end to:

How and what type boundary conditions (I was thinking about the simplest or third type) to be able to determine the values on the y-axis on the graph. For example, the values started at -10, and ended at 10 (at a point (x, -10), (x, 10) in the coordinate system for a predetermined x, for example, from 0 to 20 which start at the point (0, -10 ) and stop at the point (20,10)). My main purpose is to collect these three solutions  to one equation T (x) = az * Tz (x) + and * Tw (x) + ag * Tg (x), and the ends of the graph, they should be in the above-mentioned points (0, -10 ) - start and (20,10) - stop.

Now thank you very much for the advice.

Ewa.

### Solving system of ODEs by Laplace transform...

October 11 2014
0 1

I'm trying to solve this system of ODEs by Laplace transform.

> de1 := d^2*y(t)/dt^2 = y(t)+3*x(t)

> de2 := d^2*x(t)/dt^2 = 4*y(t)-4*exp(t)

with initial conditions

> ICs := y(0) = 2, (D(y))(0) = 3, x(0) = 1, (D(x))(0) = 2

Using

> deqns := de1, de2

and

> var := y(t), x(t)

I need to solve it for both y(t) and x(t), I have tried this by:

> dsolve({ICs, deqns}, var, method = laplace)

And

> dsolve({ICs, deqns}, y(t), method = laplace)

> dsolve({ICs, deqns}, x(t), method = laplace)

However I get this error message:

Error, (in dsolve/process_input) invalid initial condition

Any help is appreciated

### pdsolve with maple 13...

August 19 2014
0 2

I'm taking my first steps with maple and pdsolve, trying to run the example in the maplesoft support page:

http://www.maplesoft.com/support/help/Maple/view.aspx?path=examples/pdsolve_boundaryconditions

>
> restart; with(PDEtools);
> U := diff_table(u(x, t));
>

and I get a solution that is different from the web page, and when i run

Im using maple 13. Any tips about what's wrong?

regards

### Conditions in NonlinearFit?...

August 11 2014
0 11

Hello everyone,

I'm trying to do some fitting using NonlinearFit, for the coefficients I know in advance, that they have to fulfill a condition (a+b>c+1). I couldn't find a way to make Maple take this condition into consideration while fitting my data. I tried to use Parameterrange to make the difference a+b-c+1 positive, this works for linear conditions like mine but leads to computational difficulties and errors like "no improved point could be found".

Sören

### boundary condition erorr for pde...

August 05 2014
0 1

hi

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BC1 = diff(T(x, 0), y)=1000

BC2 = diff(T(x, 0.000025), y)=2000

IC = T(0,y)=0

where :

u(y)=-1.218493440*10^11*y^2+4.244913600*10^6*y+0.033

### System of PDE with initial condition...

August 01 2014
0 3

How can I solve this problem on Maple?
Can anyone help me please ... I wrote another post before but I can not solve the problem.

lambda is an experimental parameter. I have this initial condition n(x,0)=0.4, c(x,0)=0.

Thanks to everyone

### Pde system with initial condition...

July 27 2014
1 8

Dear Maple Users,

I'm beginner in Maple.

I have this system of Pde:

with lambda experimental parameter and n,c,v dependent variables. I write this on Maple but I read on internet that the solution "float(undefined)" is an error.

I will insert this initial condition: c(x,0)=0,n(x,0)=0.4

Thanks everybody

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