## Maple Integral with a parameter in the upper limit...

Hello fellows,

I am currently using Maple and surprised I can not solve the following problem. I want to use a function as the upper limit of an integral, for example

f(t) := int(1/x, x = 1 .. t) .

Could anyone tell me why Maple won't understand this?

Thank you for your help, I wish you a nice week.

Mac

## converting a rational equation into a different fo...

Hi,

I am trying to derive solutions for cubic equation using Maple.

Problem I encountered is it automatically cancles and simplifies, I cannot reach to the final form using Maple commands except modifying the equation by myself.

like,

(-108*q - 12*sqrt(12*p^3 + 81*q^2))^(1/3)/6 into (-q/2 + sqrt(p^3/27 + q^2/4))^(1/3)

Another one, even though I want this fractional form, it becomes other form automatically

(-q/2 + sqrt(p^3/27 + q^2/4))^(1/3) into (-q/2 + sqrt(12*p^3 + 81*q^2)/18)^(1/3)

Thank you.

## solving an integral...

Hi

how can i find the answer if this integral analytically

int(exp(-b*x)/(exp(-2*b*x)*a+exp(-4*x)),x);

## How to find an ODE from a curve...

Hi! my name is Euge, i live in Argentina!
I´m solving a problem that ask me to find an ODE from a family of curves,
I know this is pretty simple, I have to derive the equation two times, but i can´t find a comand in maple that helps me do that. Is there any?
Thank you!

## Threaded code gets stuck, only sometimes....

Hey there.

I've been using the threads package to parallelize some code. It's going well for the most part - my code runs way faster and I can observe with my System Monitor (ubuntu) that multiple cores are indeed being used. However, ~ 4 of every 5 times I try to run the exact same code, Maple will get stuck on a threaded calculation. If I follow the CPU usage in these instances, I see that one of the CPUs is maxed out at 100%. I am forced to quit Maple and kill the kernel process. Has anyone seen something like this before?

## dsolve an equation...

Hi

how can i solve this

dx+4*x*dy/y = dy*a*y^(-6*b-1)

to find x in terms of y

## Help to make legends apear on a plot...

Hey everone, im trying to get 2 legends to apear on my plot im animateing. The problem here is that it just wont. Could you guys help me ?

Heres the code

c := x -> piecewise(0 <= x and x <= 450000, 0.37*x, 450000 < x, 0.37*x + 0.06*(x - 450000));
g := x -> piecewise(0 <= x and x <= 558000, 0.37*x, 558000 < x, 0.37*x + 0.12*(x - 558000));
A1 := plots:-animate(plot, [g(x), x = 0 .. skat, color = blue], frames = 20, skat = 0 .. 1000000);
A2 := plots:-animate(plot, [c(x), x = 0 .. skat, color = red], frames = 20, skat = 0 .. 1000000);
Do(%Plot2 = plots:-display([A1, A2], size = [1000, 700], gridlines = true, legend=["Line 1","Line 2"],legendstyle=[font=[Lucida, roman, 14], location=bottom]));
SetProperty("Plot2", ':-play', true, ':-refresh' = true);

## Solving a trivial pde in Maple 20018...

Hi everybody,

Im trying to solve the following trivial pde using Maple 2018

pdsolve([diff(Y(x, t), t, t) = 0, Y(x, 0) = 0, (D[2](Y))(x, 1) = 0]);

Obviuosly the solution is Y(x, t) = 0, but Mapple 2018 is not giving any answer.

This works in Maple 2015.

Why is not working in Maple 2018?

Thanks,

Javier

## Plot graph - polynomial...

I have the equation y^2=𝑎𝑥^3+𝑏𝑥^2+𝑐𝑥+𝑑.

How do I plot y against x as the coefficients a, b, c and d vary?

## how can i write a number or word on the column or ...

hi

how can i write a number or word on the column or right the row of matrix as this pic

## how to evaluate a complex integrations by maple...

hi, I am trying to evaluate the following integrations (Note that; the values of alpha, lambda_1 and lambda_2) are random and they change with every iteration

 >
 >
 >
 >

## Error in rootfinding...

Hello,

Error, (in RootFinding:-Analytic) Maple was unable to allocate enough memory to complete this computation.  Please see ?alloc

What should I to do to overcome this error?

## Fitting variables to matrix eigenvalue solutions...

Hi guys,

I'm fairly new to programming as a whole, but I've currently set up a script which creates a matrix and then fills it in given a  condition. i.e if the x and y indices of the matrix are the same it has been told to add m^2F. If the y and x index differs by 3 is has been asked to fill in V3/4 and if they differ by 6 it has been asked to fill in V6/4. After the matrix is created it will then calculate the eigenvalues.

My question is as follows:

m^F is a constant and V3 and V6 are variables. I currently, manually, set a value of V3 and V6 at the top of the script and then calculate the eigenvalues. How would one go about reversing this process - i.e provide a set of eigenvalues and then perform a fit to find the best values of V3 and V6. Is this 'doable' in Maple or would it be best to use something else.

I have attached a copy of the script for viewing purposes in case what I have written is not very clear - Hindered_rotor.mw

David

## how to handled mixed conditions ?...

How 2 solve summation when M,  Z,  X are given with mixed conditions?

## Error, unable to convert to an explicit first-orde...

Hello everyone, I'm trying to run a simple calculation (Water flowing out of a pressurised container) using a combination of conservation of energy and conservation of mass. I have working models of the same system without pressurisation (purely gravity working) which work fine in Maple, but when re-writing the pressure as a function of the height of the water I receive the error:

"Error, (in DEtools/convertsys) unable to convert to an explicit first-order system".

The formula used is:

"Eq1:= -Rho_Water * A_Barrell * v_Barrel = Rho_Water * A_Nozzle * v_Nozzle"

Which returns:

"Eq1:= -25.23733555 * d/dt h_Water(t) = 0.5982 * (-190.1309944 - 13.64385474 * h_Water(t) + (d/dt h_Water(t))2)1/2"

With initial condition:

"ics1:= h_Water(0) = 0.2"

After giving the command:

"Sol1:= dsolve({Eq1, ics1}, numeric)"

Maple returns the aforementioned error. When trying to solve non-numerically the output is a list filled with "RootOf" and "_Z". Instinctively I would say the square root in the second part of the equation is the problem here, but I would not know how to fix this. Does anybody have a quick fix for this problem? Or is there a fundamental issue with the equation? Thank you in advance!

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