How to conver a patial differetial equation to ordinary differential equation with or without dchange?
 

Download pde_to_ode.mw

I make more and more use of the FunctionAdvisor. I have started to apply rules from the advisor to expressions. Here are two examples with questions:

Any advice?

Download Applying_identities_from_FunctionAdivisor.mw

Dear Users!

I hope everyone is fine here. I want to solve the following system of PDEs associated with Robin-type boundary conditions. But got the error. Kindly help me to fix this issue. Thanks

restart; TT := 0.1e-2; l := 1/5; b[1] := .18; b[2] := 2*10^(-9); k[1] := 1.3*10^(-7); k[-1] := 24; k[2] := 7.2; p := .9997; d[1] := 0.412e-1; f := .2988*10^8; g := 2.02*10^7; s := 1.36*10^4; E[0] := 3.3*10^5; T1[0] := .5*10^9; C1[0] := 3.3*10^5; alpha[0] := 10^(-10); D1 := 10^(-6); D2 := 10^(-2); D3 := 10^(-6); d[4] := 1.155*10^(-2); t[0] := 1/D1; kappa := 10^4; k[3] := 300*(24*60); chi := 0; sigma := d[1]*t[0]; rho := f*t[0]*C1[0]/(E[0]*T1[0]); mu := k[1]*t[0]*T1[0]; eta := g/T1[0]; epsilon := t[0]*C1[0]*(p*k[2]+k[-1])/E[0]; omega := D3/D1; beta1 := b[1]*t[0]; beta2 := b[2]*T1[0]; phi := k[1]*t[0]*E[0]; lambda := t[0]*C1[0]*(k[-1]+k[2]*(1-p))/T1[0]; psi := t[0]*(k[-1]+k[2]); gamma1 := chi*alpha[0]/D1; delta := D2/D1; kappa := k[3]*t[0]*C1[0]/alpha[0]; xi := d[4]*t[0]; PDE1 := diff(u(y, t), t) = diff(u(y, t), y, y)-gamma1*(u(y, t)*(diff(theta(y, t), y, y))+(diff(u(y, t), y))*(diff(theta(y, t), y)))+sigma*piecewise(y <= l, 0, 1)+rho*C(y, t)/(eta+T(y, t))-sigma*u(y, t)-mu*u(y, t)*T(y, t)+epsilon*C(y, t); PDE2 := diff(theta(y, t), t) = delta*(diff(theta(y, t), y, y))+kappa*C(y, t)-xi*theta(y, t); PDE3 := diff(T(y, t), t) = omega*(diff(T(y, t), y, y))+beta1*(1-beta2*T(y, t))*T(y, t)-phi*u(y, t)*T(y, t)+lambda*C(y, t); PDE4 := diff(C(y, t), t) = mu*u(y, t)*T(y, t)-psi*C(y, t); ICs := u(y, 0) = piecewise(0 <= y and y <= l, 0, 1-exp(-1000*(x-l)^2)), T(y, 0) = piecewise(0 <= y and y <= l, 1-exp(-1000*(x-l)^2), 0), C(y, 0) = piecewise(l-epsilon <= y and y <= l+epsilon, exp(-1000*(x-l)^2), 1-exp(-1000*(x-l)^2)), theta(y, 0) = 0; BCs := {(D[1](C))(0, t) = 0, (D[1](C))(1, t) = 0, (D[1](T))(0, t) = 0, (D[1](T))(1, t) = 0, (D[1](theta))(0, t) = 0, (D[1](theta))(1, t) = 0, (D[1](u))(0, t) = 0, (D[1](u))(1, t) = 0};

PDE:= {PDE1, PDE2, PDE3, PDE4}; pds := pdsolve(PDE, {ICs}, BCs, numeric, spacestep = 1/100, timestep = 1/100);

Error, (in pdsolve/numeric/process_PDEs) specified dependent variable(s) {(D[1](C))(0, t) = 0, (D[1](C))(1, t) = 0, (D[1](T))(0, t) = 0, (D[1](T))(1, t) = 0, (D[1](theta))(0, t) = 0, (D[1](theta))(1, t) = 0, (D[1](u))(0, t) = 0, (D[1](u))(1, t) = 0} not present in input PDE
 

Good afternoon, I'm trying to simplify or that Maple gives me the factor of (3a - 3) and it doesn't. The result that should be thrown is 3(a-1).

Hi.

When trying to open my document it says:
''There were problems during the loading process, Your worksheet may become incomplete.''

Would you mind helping me?
I saw some scripts on how to fix it, but simply can't solve it myself.

Regards Samuel

Basismat_2_noter.mw

Hello do u know how to make this code more optimal? this is very long time to plot.

g := evalf((Beta(1/4, 1/4)/2)^4);

A := Pi*r*cos(theta) - Re(WeierstrassZeta(r*exp(theta*I), g, 0) + Pi*WeierstrassPPrime(r*exp(theta*I), g, 0)/g);
B := Pi*r*sin(theta) + Im(WeierstrassZeta(r*exp(theta*I), g, 0) - Pi*WeierstrassPPrime(r*exp(theta*I), g, 0)/g);
C := sqrt(6*Pi/g)*Re(WeierstrassP(r*exp(theta*I), g, 0));

plot3d([A, B, C], r = 1/5 .. 4/5, theta = -Pi .. Pi, view = [-8 .. 8, -8 .. 8, -8 .. 8], shading = zhue, grid = [200, 200]);

Good day everyone.

I am trying to write a code with variable stepsize involving tolerance. two vectors are declare for the errors. However, I don't know how to declare the two errors in comparison with the tolerance. Please kindly help. Also, any other modification to the entire code is also welcomed. Thank you all and best regards.

The code is as attached.

Variable_step_size_Falkner.mw

Dear Maple experts,

I am running a Maple code with several lines/ curves in a plot.

For two of the curves, I use style=pointline. But in the legend the symbols on the lines are not shown. Can you advise how we can make them appear?

I have attached the file. Thank you so much! 

Download LegendPlot.mw

i want to plot this equations for P and t for  t= 0 t0 600 seconds..can u provide me how?

time-dependent_aerodynamic_pressure.mw

Download time-dependent_aerodynamic_pressure.mw

Hi!

I hope everyone is fine. I have a square matrix like the following form
A := Matrix([[10, -1, 2, 0], [-1, 11, -1, 3], [2, -1, 10, -1], [0, 3, -1, 8]]);
How to split A into three matrices D, L and U as:

D:= Matrix([[10, 0, 0, 0], [0, 11, 0, 0], [0, 0, 10, 0], [0, 0, 0, 8]]);
L := Matrix([[0, 0, 0, 0], [-1, 0, 0, 0], [2, -1, 0, 0], [0, 3, -1, 0]]);
U := Matrix([[0, -1, 2, 0], [0, 0, -1, 3], [0, 0, 0, -1], [0, 0, 0, 0]]);

I am waiting for your positive response. Please take care

Hello Everyone;

I need to solve the following nonlinear ODE

C*diff(y(x), x) + (-B0*y(x)^3 - B1*y(x)^2 - B2*y(x) - B3) = 0, y(0)=B4

where B0,B1,B2,B3 and B4 are constants. I am trying in Maple 2021, but receiving solution in the form of integral. Is that any other ways that I will be able exact solution. Maple sheet is atatched. I am waiting for your kind respose.

Thanks

Question1.mw

Download Question1.mw

Hello,

I want to create an product expression from all list elements,

e.g.

expr := createproduct([a,b,c,d,1]);

expr:= a*b*c*d

Context; I'd like to apply a function on all factos of a polynomial. I can easily map(fun,factors(apolynomial)) which will output a list. However I do not know how to get back.

Thanks for your comments!

When i try to log on to my maplesoft acount on Maple 2023 i get a messeage saying "Sign in Error: Please check your credentials and try again." i have done this multiple time double checked my password and everything, but it won't let me log on... what do i do?

Hi @Acer, and of course also hi to the whole mapleprimes comunnity.

I have a problem with the Phasors module. Very often I have to use the in calculations involving phasors. Sometimes it might make sense, since one of the involved variables are not defined as a phasor.

May I suggest that you upgrade the phasors module to a package Acer? I'd be honored to help in the testing.

Besides I have the same experience as mentioned in this question (bear over with me it's years since already): Maple 2020 Sheet now opening in 2021, 2022, and 2023 results in errors.

attached some examples:

Eksempel_8.2.mw

Example_12.3.mw

Eksempel_14.5.mw

Opgave_4_-_SHS_-_RA_ref-UL1.mw

Opgave_4_-_SHS_-_RA_ref-UL1_using_context_menu.mw

Hi everyone.

Could you please help me to obtain the results by 'solve'?

Is there any way such as numerical methods in this regard?

Fung.mws