Bill Greene

MathWorks

Con actividad desde 2012

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Solving 2 PDEs across one domain.
This documentation page shows how to specify an f-coefficient on a specific domain: <http://www.mathworks.com/help/pde/ug/sca...

casi 10 años hace | 0

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Simulation of coupled partial differential equation using MATLAB.
I took a look at your attachment and think I understand most, but not all, of the problem you are trying to solve (I don't under...

alrededor de 10 años hace | 0

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Problems with LDL factorization
Have you tried solving the over-determined system directly: x = A\b; Computing using the normal equations, A'*A, is almost...

alrededor de 10 años hace | 0

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Can I use Poisson equation or any equation with desired parameters in PDE Toolbox using Rectangular shape?
Take a look at this example: <http://www.mathworks.com/help/pde/ug/electrostatics.html> Bill

alrededor de 10 años hace | 0

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Why aren't the essential boundary conditions fulfilled?
I ran this example in R2014a of MATLAB and I do get -1 at the lower left corner (and upper right) I created the example in pd...

alrededor de 10 años hace | 0

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Solve parabolic coupled PDE's using MATLAB's pdepe solver?
Yes, pdepe can definitely solve systems of pde. In general, the u argument to the functions you define has as many rows as ther...

alrededor de 10 años hace | 0

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structured quadrilateral mesh in PDE Toolbox
There is no support for quadrilateral elements in PDE Toolbox-- either in the meshers or the computational modules. However, if...

alrededor de 10 años hace | 0

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How to define a temperature dependent parameters in a PDE Toolbox?
Yes, PDE Toolbox allows the coefficients to be functions of the dependent variables (e.g. temperature). This documentation page ...

alrededor de 10 años hace | 2

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Setting up the initial conditions for BVP4C?
From your call to bvpinit where you have this [0.01; 0.9] for the initial guess, it looks like you have 2 differential equation...

alrededor de 10 años hace | 1

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Matlab hyperbolic PDE equation errors
There are several ways to define PDE Toolbox coefficients that vary spatially. But, defining the value of the coefficient at eve...

alrededor de 10 años hace | 1

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How to solve system of three nonlinear PDE?
pdenonlin is for solving only PDE that are not a function of time. However, the parabolic function can solve equations that a...

alrededor de 10 años hace | 0

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Solve a non linear differential equation systems with only boundary conditions
You have a system of two first order differential equations so you need just two boundary conditions. I would guess that specify...

alrededor de 10 años hace | 0

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Reg. PDEPE 's internal discretization of time
pdepe uses the variable time step ODE solver, ode15s, internally. http://www.mathworks.com/help/matlab/ref/ode15s.html The...

alrededor de 10 años hace | 1

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Insert f coefficient in pdetool
Do you calculate F in fcoeff? If so, you can make it a global variable and it will retain its value between calls to fcoeff. ...

alrededor de 10 años hace | 0

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pdepe daeic12 (line 77) eror
I don't see any boundary conditions on c3. I think this may be the cause of your problem. Bill

alrededor de 10 años hace | 0

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Error solving simultaneous PDEs.
The first thing I should say is that pdepe is designed to solve systems of parabolic and elliptic PDEs. Practically this means t...

alrededor de 10 años hace | 0

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create sparse matrix from diagonal arrays
This doesn't exactly answer your question but still may be useful. This example: http://math.mit.edu/cse/codes/mit18086_poiss...

alrededor de 10 años hace | 0

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How to implement irregular, time-dependent boundary condition in PDEPE function?
I think that pr = interp1(timedata, tempdata, t) - ur; may be what you need. Assuming the lengths of timedata and temp...

alrededor de 10 años hace | 1

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How can I solve a PDE with given coefficients in time?
Take a look at this example: <http://www.mathworks.com/help/pde/ug/nonlinear-heat-transfer-in-a-thin-plate.html Nonlinear Hea...

alrededor de 10 años hace | 0

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Function of boundary conditions PDEPE
To set the temperature at each end to fittedmodel(t), you would define: pl = ul-fittedmodel(t); pr = ur-fittedmodel(t); ...

más de 10 años hace | 0

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calculate the capacitance with PDE toolbox
One of the simplest ways to calculate capacitance using PDE Toolbox is from the energy: C = 2*U/V^2 where U is the electrostatic...

más de 10 años hace | 1

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How to control times at which PDE Toolbox solves a parabolic equation?
I'm afraid I wasn't able to run your example. I believe that your fcoeff function has an error in it. I did take a look at th...

más de 10 años hace | 0

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Calculation of Jacobian for ode15s in hyperbolic/parabolic-Solver?
If the Jacobian is a function of the dependent variables (or time), ode15s will typically call pdehypdf many times during a com...

más de 10 años hace | 0

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Calculation of Jacobian for ode15s in hyperbolic/parabolic-Solver?
Hi Lena, Yes, you are correct that the Jacobian calculated in parabolic/hyperbolic is only approximate. However, in my experi...

más de 10 años hace | 0

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How to control times at which PDE Toolbox solves a parabolic equation?
>This does not yield correct results at the time values I ask it to plot the results So, why don't you request results at the...

más de 10 años hace | 0

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eigs - Error with ARPACK routine znaupd: info = -8
I'm not certain what the problem is but I can suggest something to try. I'll assume you really want around 20 eigenvalues. By...

más de 10 años hace | 0

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Does hyperbolic-solver really use a nonlinear solver?!
Hi, Unfortunately, I believe you have uncovered a bug in the hyperbolic function that occurs when you have a nonlinear equati...

más de 10 años hace | 0

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Does hyperbolic-solver really use a nonlinear solver?!
Sorry about that! Apparently this GUI is too sophisticated for me ;-) I think I got it this time. Bill

más de 10 años hace | 0

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Does hyperbolic-solver really use a nonlinear solver?!
Hi, I think that referring to gradient components in the form e.g. ux(1,:) is fine. But entering complicated nonlinear coeffi...

más de 10 años hace | 0

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Does hyperbolic-solver really use a nonlinear solver?!
Oh, sorry, I thought you were using the documented hyperbolic function. I'm afraid I have no idea why your code isn't doing wha...

más de 10 años hace | 0

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