Maple Questions and Posts

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I have final project to make a media for learning mathematic using maple. But I'm so confused to make a net of cuboid, anybody can help me? please :D

Hi,

 

I have a problem of having a problem to solve the following equation with the this error. I found out that it might be due to that I have a differential that is squared and maple could not calculate it as after square root it will have positive and negative. May I know how to overcome this other than changing my equations?

ODE_summarize.mw
 

restart; with(DEtools)

````

sol1 := alpha*(diff(f(y), y, y, y)) = -(1/4)*f(y)*(diff(f(y), y, y))*n+(1/2)*(diff(f(y), y))^2*n-(3/4)*f(y)*(diff(f(y), y, y))+(1/2)*(diff(f(y), y))^2-g(y), diff(g(y), y, y) = -(1/4)*P[r](f(y)*(diff(g(y), y))*n-4*n*(diff(f(y), y))*g(y)+3*f(y)*(diff(g(y), y)))

alpha*(diff(diff(diff(f(y), y), y), y)) = -(1/4)*f(y)*(diff(diff(f(y), y), y))*n+(1/2)*(diff(f(y), y))^2*n-(3/4)*f(y)*(diff(diff(f(y), y), y))+(1/2)*(diff(f(y), y))^2-g(y), diff(diff(g(y), y), y) = -(1/4)*P[r](f(y)*(diff(g(y), y))*n-4*n*(diff(f(y), y))*g(y)+3*f(y)*(diff(g(y), y)))

(1)

bc := (D(f))(y)

(D(f))(y)

(2)

gg := convert(bc, diff)

diff(f(y), y)

(3)

gg1 := limit(gg, y = infinity)

limit(diff(f(y), y), y = infinity)

(4)

gg2 := convert(gg1, D) = 0

limit((D(f))(y), y = infinity) = 0

(5)

gg2

(D(f))(y) = 0

(6)

bc1 := eval(f(y), y = 0) = 0, eval((D(f))(y), y = 0) = 0, convert(gg1, D) = 0, limit(g(y), y = infinity) = 0, eval(g(y), y = 0) = 1

f(0) = 0, (D(f))(0) = 0, limit((D(f))(y), y = infinity) = 0, limit(g(y), y = infinity) = 0, g(0) = 1

(7)

``

odesub1 := eval(eval(sol1, n = .6), P[r] = 0)

alpha*(diff(diff(diff(f(y), y), y), y)) = -.9000000000*f(y)*(diff(diff(f(y), y), y))+.8000000000*(diff(f(y), y))^2-g(y), diff(diff(g(y), y), y) = 0

(8)

sol2 := dsolve({bc1, odesub1}, numeric, [f(y), g(y)], output = operator, continuation = alpha, initmesh = 2400, method = bvp[midrich])

Error, (in dsolve/numeric/bvp/convertsys) unable to convert to an explicit first-order system

 

``


 

 

 

 

 

 

 

 

 

 

I have the following expression

((4*(N-i+2))*((N-i-2)*(-(N-i-4)*(N+i+2)*(N+2)*(N+4)+N^4+4*N^3+4*N^2+16*N-40)-(4*(N-1))*(2*N+3)*(N+5))+(8*(N+5))*(N^2+8*N+6))/((N-i+1)*(N-i+3)*((N-i-2)*(i+3)*(N+2)*(N+4)-(8*(N+5))*(N-1)))

The parameters i and N are nonnegative integers and i is less than or equal to N. The purpose is to make it as short as possible. Based on my experience, it could be expressed as a small binomial expression or as a sum of two or three binomials. However, by Maple commands the conversion does not give me binomials or any smaller expression.

Is there any way for the conversion to binomials or any other conversion to shorten the expression?

I appreciate any help.

i want to solve this DAE system usin Dsolve , but i obtain this error message (cannot evaluate the solution past the initial point, problem may be complex, initially singular or improperly set up), if anyone can help me ,

I am trying to export a number of matrices from maple to matlab with meaningful names.

For instance with this code:
legend := ["ini_que", "ini_que_A", "ini_que_B"];
ExportMatrix("test.mat", [r_mean_Q_ini, r_mean_Q_ini_A, r_mean_Q_ini_B], arraynames = legend, target = MATLAB);

The problem is when I open the resulting file in either python or matlab, I only get  the matrices with names "ini_que" and "ini_que_". My guess is that  long strings in arraynames are truncated and only one of the options are kept.

Is this the case and can the maximum length of the name of the matrix be changed? Or is the only way to use shorter but less readable names?

Dear all

I have an operator given below in the image. I want expand this operator upto order 5, when there are three independent variables x, y, t(i=1,2,3). The expansion can also be obtained manually, but that is always prone mistake, is the expansion posible using any routine of Differential Geometry package?

Hi guys ,

Actually i dont know how to solve the following complicated differential equations by numerical methods ,

numerical.mw

 

Thank you for your attention to this matter

That the Bernoulli numbers has z/(exp(z)-1)) as an exponentional generating functions is of course very well known. I am wondering why the gfun package doesn't seem to be able to work this out? Naive approaches like

gfun[guessgf]([seq(bernoulli(n),n=0..100)],z);

give FAIL. I would expect gfun to be able to transform the given sequence corresponding to replacing A(z) by 1/A(z), easily recognize (exp(z)-1))/z, and transform back. Perhaps the package is in need of maintenance?

Any help would be much appreciated.

Best,

Soren

 

 

Hi

Is there any idea using Maple  to compute the leg lengths  in Stewart-Gough platform ( see the following figure)

I would like to make a code using cross-product and the unit Normal N 

·       P is of length 13 and displaced in the Y direction by 10 degrees from the vertical (Z axis)

·       N is displaced in the X direction by 18 degrees from the vertical (Z axis)

·       LB is position [7 5] from the bottom plate centre in the XY plane

·       LT is in position [3.5 4.2] from the top-plate centre in the AB plane

Many thanks for any help

 

 

L := sum( 1/ln(k), k=2..n ) * ln(n)/n;
        
limit(L, n=infinity);
                               0
# Should be 1

Just curious: in Maple 2017, is it OK?

 

 

Dear sir,

in the program boundary conditions D(f)(0)=0 doesn't showing result but when use d(f)(0)=1 it will execute, why is this can you explain this ?program.mw
 

So, I'm trying to delelop an algorithm for the method of multiple scales. Starting with a simple ODE:

diff(x(t), `$`(t, 2))+x(t) = 0

After scaling, it should be written in the form:

(d/dT[0]+epsilon*d/dT[1]+epsilon^2*d/dT[2])^2*(epsilon^3*X[3]+epsilon^2*X[2]+epsilon*X[1])+epsilon*X[1]+epsilon^2*X[2]+epsilon^3*X[3] = 0

A proto-algorithm would be:

restart;
ode := diff(x(t), `$`(t, 2))+x(t) = 0;
i_ini := 1; i_fin := 3; j_ini := 0; j_fin := 2;
PDEtools:-dchange({t = sum(epsilon^j*T[j], j = j_ini .. j_fin), x(t) = sum(epsilon^i*X[i](T[1]), i = i_ini .. i_fin)}, ode, [{T[0], T[1], T[2]}, {X[1], X[2], X[3]}])

It is not working, though. Could anyone help me out?

Thanks in advance.

hello everyone. i wanna ask. how to do a coding of stability region on diagonally implicit Runge-Kutta for order 3 and order 4? Thank you in advanced :) 

Hello,

I am trying to solve analytically a simple system of partial differential equations with boundary conditions and I am not able to do it. Even in the very simple case of

pdsolve([diff(u(x, y, t), y, y) = 0, diff(p(x, y, t), y) = 0, u(x, 0, t) = 1, (D[2](u))(x, 1, t) = 0, p(x, 1, t) = 2], [p(x, y, t), u(x, y, t)]);

I don't get any answer.  However if I remove the boundary conditions I get the right answer

pdsolve([diff(u(x, y, t), y, y) = 0, diff(p(x, y, t), y) = 0], [{p(x, y, t), u(x, y, t)}]);
 {p(x, y, t) = _F3(x, t), u(x, y, t) = _F1(x, t) y + _F2(x, t)}

Can maple 2015 solve analytically systems of partial differential equations with boundary conditions? I have not been able to find any example anywhere.

Thanks a lot for your help.

Javier

Hi Mapleprimes,

We know that '' rsolve '' is a recurrence equation solver.  It is more than an expression simplifier.

Congratulations to the Maple computer algebra team for creating such a great computer tool.  simply want to know more.

rsolve_on_May_16_2017.pdf

Surely there are many steps to determine the values to place.

Regards,

Matt

 

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