Hello,

I have a ode system which I use dsolve/numeric for it?

By default dsolve use rkf45 but the result is not very exact. The error is high.

How can I make dsolve more accurate?

Which method I have to use?

It is initial value problem that I use dsolve/numeric for it.

Thanks so much.

Bye

Problems: Calculate Fourier Transforms of:
>
> f(t)=1 for (1<=|t|<=2) and 0 otherwise
>
> f(t)=cos wt[H(t+1/2T)-H(t-1/2t]
>
> f(t)=exp(at) (t<=0), (a>a) and exp(-at) (t>0)
>
> f(t)=exp(-at) sin wt H(t)
>
> note: w is omega and T is Tau, H is Heaviside
 

Not sure how to do these problems with maple.

I need help making a 3D plot of a numerical solution to Euler's Equation for Rigid Bodies(Non-linear Differential Equation). The solution to this equation are the angular velocity components w1,w2,w3. I am able to plot each component using the following commands, plots[odeplot](numericalsol,[t,w[1](t)],0..20); plots[odeplot](numericalsol,[t,w[2](t)],0..20); plots[odeplot](numericalsol,[t,w[3](t)],0..20); However, how do I make a 3D plot using these numerical solutions?? Any help is greatly appreciated.

Hi:

I often need to change a few parameters and rerun the whole worksheet. In some cases however, some of the sections should not be executed. Is there a way to quickly comment/uncomment out a given section? If so, how?

thanks.

Hello all,

I have an ODE system called RedSys which is below and incons1 which is its initial condition.

When I want to solve this system by dsolve numeric with this command:

dsolve((convert(RedSys, set)union incons1), numeric, implicit = true);

I face an error which says :

system should be linear in leading derivative. However when check I do not see any non linearity.

could you please let me know what should I do to solve this system by dsolve/numeric?

Thanks so much,

 

Hi

I have a problem with the fact that maple not always knows the difference between pi and -pi. Try for example these three lines:

> evalf((-5-2*I)*(exp(-(.999999999*I)*Pi))^(1/2-0.8e-1*I)); 

> evalf((-5-2*I)*(exp(-I*Pi))^(1/2-0.8e-1*I));

> evalf((-5-2*I)*(exp(I*Pi))^(1/2-0.8e-1*I));

They have significantly different results where the line with the exp( - I*Pi) is interpreted as exp(I*Pi).

Is there anyway to avoid this?

I use maple 13

Thanks in advance

Best regards
Brian

In a Maplet, how do I access an expression entered into a MathMLEditor to use as a Maple expression (to plot, evaluate, simplify etc.)?

Hi.  I want to plot the function U in terms of x and y,

U :=2*diff(p(x,t),x)*diff(q(y,t),y)/(p(x,t) + q(y,t) + a[0])^2;

where

I would appreciate if anyone could solve this problem. (please see attached pdf or mw file )
The error messages is:  Error, (in ExecuteQuery) unknown API type  (I am trying to access data from a SQL server)

Download 8342_Maple is being Stupid.pdf
View file details

I used the solve command to solve for the unknown b , i do have the solution listed in the book...but when i try to solve it as follows

solve((tan(Pi/18)=(2*cot(b)*((3.4^2)*sin(b^2)-1))/((3.4^2)*(1.4+cos(2*b))+2)),b);

since maple takes values in radians(10 deg)

i get the message as "solutions may have been lost"

Am i doing anything wrong ?

Hi.

This one is rather simple. Anyway I do not get the right way to do it.

I´d like to redefine showassumed and set it to zero.

Can anyone give me an example how to do it?

Thanks.

I tried the following:

restart;
with(Statistics):
X1 := RandomVariable(Binomial(n, p)):
DARA := t->piecewise(0<t,log(t),0):

0 < n, n::posint, 0 <= p, p <= 1:
 

ExpectedValue(DARA(X1));                                        
g1 := simplify(%) = DARA(s);
k1 := solve(g1, s);
 

Hi.

Does anyone know, why or when to use the assume command as opposed to just defining the assumptions?

e.g.

instead of typing:

assume(0 < sigma);

i could just write:

0 < sigma;

right?

I am not able to use colors flexibly in contourplot3d. So, I am trying another way to get my plot. But I am not exactly getting my result. This is what I am trying to do. I need help with these three steps. 1) For Latitude from -10 degrees to 10 degrees and longitude from -30 degrees to 30 degrees, I need to calculate aa:=1.4*cos(latitude)-2*sin(longitude). 2)The above value of 'aa' gives color. (eg. if aa<><><>3 color= red etc) 3) Then plot this point with color from step 2 at (x,y) given by

Hi,
not being used to work with Maple, I cannot figure out how to solve the following problem.

I want to verify if the positive semidefiniteness of a given 20x20 matrix A (depending on 10 real variables x_1, ..., x_10) implies the positive semidefiniteness of another 4x4 matrix B (depending on the same 10 variables). The entries of each matrix are linear in the given variables, at most depending on 3 variables. The 20x20 matrix is rather sparse.

What I tried is the following: