Community Profile

# Josh Meyer

Last seen: 9 dagar ago Active since 2013

All

#### Content Feed

View by

List of built-in data sets, please
In R2021b, there is now a documentation page with a selection of useful data sets that are in MATLAB: MATLAB Example Data Sets

| accepted

Filtration modelisation pdepe derivation problem
Is phi supposed to be a function of x? You currently have phi=linspace(0,0.7,100); and xmesh=linspace(0,0.5e-6,50); So, ...

mer än ett år ago | 0

Can pdepe be used when there is a boundary condition in the centre of the system - Invasion assay
This example shows how to solve a system where there is a material interface: https://www.mathworks.com/help/matlab/math/solve-...

mer än ett år ago | 0

ODE System with 4 equations
When you have a system of equations, each equation gets its own spot in the solution vector y. With the conventions y(1) ...

ungefär 2 år ago | 0

| accepted

How would I manipulate the following functions to use a tall array?
First you need to make a datastore that references the underlying files for each array (one datastore per array). Then you can c...

mer än 2 år ago | 0

possibility to add a timeror on ODE15s which after a certain time limit, the solver is stopped or gives a null output
You could implement an event function to do that: https://www.mathworks.com/help/matlab/math/ode-event-location.html Use start...

mer än 2 år ago | 0

Solve heat problem by using pdepe
Assuming you want to enforce pr = ur+20; at t=0.03, then you can split the problem into two sub-problems that are solved separat...

mer än 2 år ago | 0

Where can I get a samaritan to help me with my code of a Reaction–Diffusion Delayed Neural Networks
You should be able to use pdepe. Just calculate tau in the pdefun function and pass the delayed time value when you call the sub...

mer än 2 år ago | 0

Boundary conditions for a ring PDE
pdepe does not allow for time derivatives in the boundary conditions. The boundary conditions are expressed in terms of the flux...

mer än 2 år ago | 0

how i can solve the following PDE using periodic boundry coditions
Periodic boundary conditions require that when something leaves one boundary with a certain velocity, it enters the boundary on ...

mer än 2 år ago | 0

| accepted

PDEPE: How to set I.C as a variable?
pdepe has expectations for the initial condition function. Namely, that it will use the functional signature: function u0 = icf...

mer än 2 år ago | 0

Writing PDE boundary conditions
pdepe expects the boundary conditions to be written in a standardized form: Notice that only p can depend on the variable bei...

mer än 2 år ago | 0

What is the “pdentrp” function in the “pdepe” function?
This is an internal, private helper function, so it does not have documentation beyond help text. You can access the file with t...

mer än 2 år ago | 1

Retaining the max value during scattered data interpolation
You'll need to do this manually before calling scatteredInterpolant. There are a few ways to do it, you could use a logical mask...

nästan 3 år ago | 0

| accepted

PCG and MINRES question
Since A*x = b, the sizes of the variables must be: A * x = b (M-by-N) * (N-by-1) = (M-by-1) But since alm...

nästan 3 år ago | 0

Getting the intermediate solutions in an iterative solver
While the functions themselves don't return intermediate results, consider that the resvec output of all the iterative solvers r...

nästan 3 år ago | 0

why convergence is not happening in pcg function ?
There are two things to notice here: In the first message you printed where PCG converges after 1 iteration, this is an indicat...

nästan 3 år ago | 0

PCG on a large sparse matrix from Finite difference method
Yes, you can provide the coefficient matrix as a function handle instead of a numeric matrix. This is because PCG, like many of ...

nästan 3 år ago | 0

Best integration method to integrate this oscilating function
integral can handle oscillatory integrands as long as there aren't too many oscillations, and you supply plenty of WayPoints in ...

nästan 3 år ago | 0

Processing Data in a Tall Array
findgroups and splitapply work with tall arrays, so don't worry about using tall.transform or tall.reduce for this simple task. ...

ungefär 3 år ago | 0

How does integral2 work?
The basic principle of numeric integration is you are calculating the area under the curve by splitting it up into smaller piece...

ungefär 3 år ago | 0

| accepted

Problem with boundary conditions for PDEPE
From the doc for pdepe, "When m > 0 and a = 0, boundedness of the solution near x = 0 requires that the flux f vanish at a = 0....

ungefär 3 år ago | 0

| accepted

what's the difference in accuracy between solving a stiff problem by ode15s and ode45?
Stiffness is more of an issue of stability than accuracy. Nonstiff solvers can solve stiff problems, it just takes them a long t...

mer än 3 år ago | 1

Change font size of node name in a graph
Several new properties were added to GraphPlot objects in R2018b to enable customization of node and edge labels. In particular ...

mer än 3 år ago | 3

| accepted

Problems with pdepe with disconnected variables in c, f and s
c, f, and s are expected to be column vectors with length equal to the number of equations being solved. Since you have 1 equati...

mer än 3 år ago | 1

| accepted

Implementing boundary condition in pdepe
The form for the boundary conditions expected by the solver is Since you have a system of two equations, each p and q should ...

mer än 3 år ago | 0

pdepe help! (boundry condition in PDE solver)
Your boundary condition function includes the line pl = ul-TT(i); TT(i) is not defined within view of the function, so that i...

mer än 3 år ago | 2

| accepted

Submitted

Plotting the Binomial Coefficient
Live script that plots the binomial coefficient over all positive and negative argument combos.

Solved

Project Euler: Problem 2, Sum of even Fibonacci
Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 te...

nästan 4 år ago

Solved

Triangle sequence
A sequence of triangles is constructed in the following way: 1) the first triangle is Pythagoras' 3-4-5 triangle 2) the s...

nästan 4 år ago