Download question_13.12.06.mw

I have following expression

f:=t->((1/8)*s^2*sinh(4*t)+t+(1/2)*s^2*t+s*sinh(2*t))/(1+s*cosh(2*t))

which is 1 solution of the ODE

ode2 := -(diff(y(t), t, t))+(4-12/(1+s*cosh(2*t))+(8*(-s^2+1))/(1+s*cosh(2*t))^2)*y(t) = 0

Now I wanted to construct 2 linear independent solutions via:

f1:=f(t_b-t)

f2:=f(t-t_a)

and calculate the Wronskian:

with(LinearAlgebra); with(VectorCalculus)

Determinant(Wronskian([f(t_b-t), f(t-t_a)], t))

Since I know these functions are solutions of the second order ODE which does not contain any first order derivative the Wronskian should be a constant. Unfortunately Maple has a hard time to simplify it since the epxression is a little big. Is it my fault or has anyone an idea what to do?

An economy consists of service and food sectors. Assume that to produce $1 worth of service consumes 50 cents worth of service and 20 cents worth of food,and to produce $1 worth of food consumes 40 cents worth of serives and 20 cents worth of food. Assume that there is an external demand for $2 million worth of serices and $12 million worth of food.

a)Determine the comsumption matrix C for this economy.

b)In order to satisfy the demand, how much of each must be produce?(Find the production vector that will satisfy the demand.)

c)For this production vector, what is the value of serices that is consumed internally by the food industry ?

Hello, I am trying to do a fourier transfrom using the package < DiscreteTransfroms >.

The function is an gaussian function for now,

Here is the code I tried

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

restart

with(DiscreteTransform):

> X := Vector(1000, proc (k) options operator, arrow; (1/200)*k-5/2 end proc);
> Y := Vector(1000, proc (k) options operator, arrow; evalf(exp(-10*((1/100)*k-5)^2)) end proc);

> X2, Y2 := FourierTransform(X, Y);
Vector[column](%id = 18446744080244879358),

Vector[column](%id = 18446744080244879478)
> plot(X2, Re(Y2));

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

The program returns two vector, X2 and Y2 who are supposed to be the fourier transforme of a gaussian so.. a gausian but when I plot the result X2 on the horizontal and Y2 on vertical, the graph doesn't resemble a gaussian function or any function at all.

Please help!!

Alex

4th_order.mw How can one solve this problem with maple?

> restart;
> Digits := 10;
> m := 11;
> P := 100;
> alpha := 1;
> F[0] := 0;
> F[1] := epsilon;
> epsilon := 0;
> F[2] := A;
> T[0] := -T[1]/alpha-1;
> T[1] := B;
> for k from 0 to m do F[k+3] := (-(sum(F[k-r+2]*F[r]*(k-r+2)*(k-r+1), r = 0 .. k))-1+sum(F[r+1]*F[k-r+1]*(r+1)*(k-r+1), r = 0 .. k))*factorial(k)/factorial(k+3); T[k+2] := -P*(sum(F[r]*T[k-r+1]*(k-r+1), r = 0 .. k))*factorial(k)/factorial(k+2) end do;
> f := 0;
> t := 0;
>
> for k from 0 to m do f := f+F[k]*eta^k; t := t+T[k]*eta^k end do;
> print(f);
> print(t)

> with(numapprox);
> pade(f, eta, [4, 4]);

>pade(t, eta, [4, 4])

>solve({limit(pade(f, eta, [4, 4]), eta = infinity) = 0., limit(pade(t, eta, [4, 4]), eta = infinity) = 0.}, [A, B])

Hi!

Say, I got an expression that depends on two variables, x and y. How can I tell Maple, that y is actually just a (real) constant, so y does not depend on x?

Because when I apply a differentiation with the "D" - command, it would always also write out expressions, where y is differentiated w.r.t. x.

Thanks!

Hi There,

Can any one correct me the mistake in the following differentiation:

Above command gives the following error:

Error, (in simpl/abs) abs is not differentiable at non-real arguments

The differential equation I'm solving for is:

Hello fellow Maple users. 
I have been useing Maple for 5 month now and i think its a great program. But sometimes i find it a bit difficult to use. 
When i plot a function i would like to see the function on the line in the plot that represents the funtion. So if have several lines representing different functions, i would Maple to highlight the function when i hower over the function 
with the mouse .. Is this posible ? I know its posible in Inspires CAS. 

It must be posible for Maple to label the plots with the function ??? If not Maple programmers got a job...

I have a problem in excuting this differential equation in maple it takes a long time but yet no result.

> restart;

> Delta:= epsilon[2]-epsilon[1];

> epsilon[y] := epsilon[2]-(1/4)*Delta*(1-tanh(a*y))^2;

 > z:= tanh(a*y) ;

 > ODE[4]:= diff(Y(y),y,y)- ( a/2* Delta *(1-z)*(z^2-1))/(epsilon[2]- Delta*(1-z)/4)* diff(Y(y),y)-( beta^2+ mu[0]*epsilon[y]*omega^2)*Y(y) = 0;

> dsolve(ODE[4],Y(y));

does this always occur or i do have problem with my version of maple 15, 7 and 16.

Thank you, looking forward for your answers.

I have created a simple proc to return true or false depending on the value in a list of values.  now i would like to filter out the falses and return the actual value that is true from the list.

sol := dsolve([ode2, theta(0) = (1/180)*Pi*10, (D(theta))(0) = 0], numeric)

sol(0)

[t = 0., theta(t) = .174532925199433, diff(theta(t), t) = 0.]

given a numerical solution in the above form, how can I integrate a function

f(theta(t)) numerically?

I tried to isolate theta(t) first:

x:=t->rhs(op(2,sol(t)))

But I can't integrate

phi:=t->int(x(t),t=0..t)

I am having some difficulty animating the function shown in the attached file.  I am going to create an animation which will show the curve as a function of t.  My first question is that there is no way to compute K_n because the initial conditions I have are only given as arbritary functions F(z),G(z).  So I am not really sure how to proceed here.

My second question is that I also want to plot the Z dependent part of y as a function of z/b.  I have tried to incorporate this into Maple, however, all I get back is that there are 'unexpected variables present'

Thanks.

Is it possible to assign a matrix given values/expressions?

Instead of assigning each element separately like in the example below: