please help me

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Dear Community,

I have a four compartment flow model described with the following system of linear ODEs:

diff(L[1](t), t) = L[2](t)/T[21] - L[1](t)/T[12]

diff(L[2](t), t) = L[1](t)/T[12] - L[2](t)/T[21] + L[3](t)/T[32] - L[2](t)/T[23] + Q(t)

diff(L[3](t), t) = L[2](t)/T[23] - L[3](t)/T[32] + L[4](t)/T[43] - L[3](t)/T[34]

diff(L[4](t), t) = L[3](t)/T[34] - L[4](t)/T[43]

(For easier readability I’ve also described the problem in the attached FourCompartmentModelDescription.docx Word file.)

The time constants are as follows:

T₁₂ = 23.1481 d

T₂₁ = 5.4537 d

T₂₃ =  9.752 d

T₃₂ = 14.9007 d

T₃₄ = 8.8235 d

T₄₃ = 363.7255 d

Initial conditions are as follows:

L₁(0) = 2500.

L₂(0) = 589.

L₃(0) = 900.

L₄(0) = 37100.

Simulation should run from 0 to 400 d.

Could you pls. help me, to solve it numerically in Maple? As a solution I would need L₁(t), L₂(t), L₃(t) and L₄(t) both numerically and graphically. I used Maple to solve ODEs previously, but this time I don’t know, how to correctly specify the problem with an external, tabulated source. I’ve also prepared and attached a Maple worksheet, but did not try to run it yet. (FourCompartments.mw). The external Q(t) source for compartment 2 is attached as Source.xlsx. Should I've forgotten something, pls. let me know.

Your kind help is appreciated in advance,

best regards

Andras

MaplePrimesFourCompartmentModelDescription.docx

FourCompartments.mw

Source.xlsx

Hi everyone.

I have a 2D function and I wanna after Differentiating from it with respect to tau (at any amount of sigma value) and equaling this derivative to zero solve the infinite system of equations.

P[n](tau)==LegendreP(n - 1/2, cosh(tau)) , Q[n](tau)==LegendreQ(n - 1/2, cosh(tau)) 

are Legendre function.

Thanks in advanced

FUNCTION_f.mw

Download FUNCTION_f.mw

The following transfer function has zero/pole cancelation. I am trying to create a transfer function object, but Maple automatically simplifies the transfer function before it gets to the DynamicSystem call, which result in different output than what I expected.

I do set the cancellation=false option, even though this is the default. The problem is Maple does pole/zero cancelation before the call.

I tried to add '' around it to delay evaluation, but it did not work.  

restart;
alias(DS=DynamicSystems):
DS:-SystemOptions(cancellation=false,complexfreqvar=s):
tf:=DS:-TransferFunction('-(s - 1)/((-2 + s)*(s - 1))'):
DS:-PrintSystem(tf)

You can see it did pole/zero cancelation.

In Matlab and Mathematica, this does not happen. For example

Clear["Global`*"];
sys = TransferFunctionModel[-(s - 1)/((-2 + s) (s - 1)), s]

Same with Matlab:

>> s=tf('s');
>> sys_tf =-(s - 1)/((-2 + s)*(s - 1))

sys_tf =
 
     -s + 1
  -------------
  s^2 - 3 s + 2
 
Continuous-time transfer function.

What do I need to do in Maple to keep the transfer function without pole/zero cancelation (this affects the state space realization later on when this cancelation happens)

I am using Maple 2019 at this moment as Maple 2020 is busy.

I am using Maple to solve a system of ODEs numerically. Right now, I want to find the integration of the output of the system of ODEs. How it is possible to do this? 

F := dsolve(ODESys union ICs, {y0(t), y1(t), y2(t), y3(t)}, type = numeric)

Y0 := t -> rhs(op(2, F(t)))

Now, I want to find int(Y0,t=0..1).

How I can prove the following equation in red box.

Also, Pn(v) and qn(v) are the real combinations of half-integer Legendre functions.

For more details please see 

https://math.stackexchange.com/questions/2746660/potential-flow-around-a-torus-laplace-equation-in-toroidal-coordinates/3809487#3809487

Hello

I need Nu[a] in the label of y-axis.

i am writing      labels = [eta, 'Nu[a]'(eta)] but I am not getting. Please help me for writing correct code.

Here are 4 statements that attempt to use invlaplace on the exponential function. Two work, two don't.

Does anyone know why the two that don't work do that?

Thank you.

__________________________

with(inttrans);
[addtable, fourier, fouriercos, fouriersin, hankel, hilbert,   invfourier, invhilbert, invlaplace, invmellin, laplace, mellin,   savetable]
invlaplace(exp(-s),s,t);
                          Dirac(t - 1)
invlaplace(exp(s),s,t);
                    invlaplace(exp(s), s, t)
invlaplace(exp(s),s,t) assuming s<0,s::real;
                    invlaplace(exp(s), s, t)

invlaplace(exp(-s),s,t) assuming s<0,s::real;
                          Dirac(t - 1)
What is going on here?
 

Can anyone kindly tell me why isn't "evalm" working even with all the neccessary varaibles have corresponding values? 

Thank you!

Here is my code:

The Help page Physics/tensors-a complete guide states that spacetime metrics from Kramer et al. are referenced by chapter, section, and equation number, e.g., g_[[12, 16, 1]]. But there is no section 16 in Ch 12 and equations within each chapter are numbered sequentially without reference to section. By playing around it seems that in fact the first number is chapter, the second number is equation number, and the third number refers to subcases of the metric, when they are specified in the text. Is that correct?

Also, the output I get from say g_[[27, 27, 1]], or any other attempt  made, is just the metric, without any specification of the coordinates etc, which the Help pages susggest should be part of the output.

Hi.

I am calculating an integral but I cannot get the result.
Can you help me.
I provide the file.

Tank you

Regards

integral_doubt.mw
 

Download integral_doubt.mw

In this figure, y axis scale is -1, -0.5,0,0.5,1.

i need that scale -1, -0.1, -0.2 -0.3......1

how to change?

How I can remove RootOf from the solution?

thanks.

root.mw

Hi,

I just wondering if I could write a variable as y' since when I try it, it will automatically diffrentiate the subject.

Thank you.

I have the following program which constructs the multiplication table, CI, for a matrix Lie algebra and evaluates the difference between CI's row dimension and its rank. The code is a little convoluted because "LieTable" formats the entries very strangely and forces incorrect rank values.

The matrix CI is constructed rather quickly (within a few seconds), and everything works well with "small" examples (up to 12 basis elements has evaluated within seconds). However, the example I've included is for a 27-dimensional Lie algebra. As I stated, CI is constructed quickly, even in larger examples, but the rank evaluation (i.e., LinearAlgebra:-Rank(CI)) has never completed for the example I've included. I let it run for about 3 hours before shutting it down.

I have an older Macbook Air which I am using to run these computations. Could this simply be an issue of not enough computing power?

I have attempted to import the matrix CI into Mathematica (to see if it was simply a limitation of Maple), but that's its own headache (reads entries of the matrix incorrectly).

Any recommendations would help. If this is an issue of computing power, I can get access to a more powerful system soon. It doesn't seem that the code itself would cause the issue, since it is not the construction of the matrix which is giving me issues, it is the evaluation of the rank. I am rather naive about Maple (and programming in general) though, so I may be wrong.

Index_and_Contact.mw