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Sylvester
Last activity 2024-6-26

Geometry-Based Stochastic Channel Modeling

Kindly link me to the Channel Modeling Group.

I read and compreheneded a paper on channel modeling "An Adaptive Geometry-Based Stochastic Model for Non-Isotropic MIMO Mobile-to-Mobile Channels" except the graphical results obtained from the MATLAB codes. I have tried to replicate the same graphs but to no avail from my codes. And I am really interested in the topic, i have even written to the authors of the paper but as usual, there is no reply from them. Kindly assist if possible.

wireless channel modeling

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Saleem
Last activity 2024-6-27

Where to find coding and algorithms problems with solutions?

Hi, I'm looking for sites where I can find coding & algorithms problems and their solutions. I'm doing this workshop in college and I'll need some problems to go over with the students and explain how Matlab works by solving the problems with them and then reviewing and going over different solution options. Does anyone know a website like that? I've tried looking in the Matlab Cody By Mathworks, but didn't exactly find what I'm looking for. Thanks in advance.

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Image Analyst
Last activity 2024-11-6

Ask Me Anything about image analysis or the Mathworks community

Hello, everyone! I’m Mark Hayworth, but you might know me better in the community as Image Analyst. I've been using MATLAB since 2006 (18 years). My background spans a rich career as a former senior scientist and inventor at The Procter & Gamble Company (HQ in Cincinnati). I hold both master’s & Ph.D. degrees in optical sciences from the College of Optical Sciences at the University of Arizona, specializing in imaging, image processing, and image analysis. I have 40+ years of military, academic, and industrial experience with image analysis programming and algorithm development. I have experience designing custom light booths and other imaging systems. I also work with color and monochrome imaging, video analysis, thermal, ultraviolet, hyperspectral, CT, MRI, radiography, profilometry, microscopy, NIR, and Raman spectroscopy, etc. on a huge variety of subjects.

I'm thrilled to participate in MATLAB Central's Ask Me Anything (AMA) session, a fantastic platform for knowledge sharing and community engagement. Following Adam Danz’s insightful AMA on staff contributors in the Answers forum, I’d like to discuss topics in the area of image analysis and processing. I invite you to ask me anything related to this field, whether you're seeking recommendations on tools, looking for tips and tricks, my background, or career development advice. Additionally, I'm more than willing to share insights from my experiences in the MATLAB Answers community, File Exchange, and my role as a member of the Community Advisory Board. If you have questions related to your specific images or your custom MATLAB code though, I'll invite you to ask those in the Answers forum. It's a more appropriate forum for those kinds of questions, plus you can get the benefit of other experts offering their solutions in addition to me.

For the coming weeks, I'll be here to engage with your questions and help shed light on any topics you're curious about.

108

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David
Last activity 2024-6-17

Week of June 17th - Must-See MATLAB Central Posts

Hello, everyone!

Over the past few weeks, our community has been buzzing with activity, showcasing the incredible depth of knowledge, creativity, and innovation that makes this forum such a vibrant place. Today, we're excited to highlight some of the noteworthy contributions that have sparked discussions, offered insights, and shared knowledge across various topics. Let's dive in!

Interesting Questions

Proving one function is greater than other? by Fatima Majeed

Fatima Majeed brings us a thought-provoking mathematical challenge, delving into inequalities and the realms beyond (e^e). If you're up for a mathematical journey, this question is a must-see!

How to split/segment csv file into multiple sections? by lil brain

lil brain tackles a practical problem many of us have faced: efficiently segmenting a CSV file based on specific criteria. This post is not only a query but a learning opportunity for anyone dealing with similar data manipulation challenges.

Popular Discussions

Trick: Easy Digit Manipulation by goc3

Discover a simple yet effective trick for digit manipulation from goc3. This tip is especially handy for those frequenting Cody challenges or anyone interested in enhancing their number handling skills in MATLAB.

Run Code in Discussions Area! by Chen Lin

Chen Lin shares an exciting update about the 'Run Code' feature in the Discussions area, highlighting how our community can now directly execute and share code snippets within discussions. This feature marks a significant enhancement in how we interact and solve problems together.

From the Blogs

A Deep Dive into EEG Analysis for Predicting Neurological Outcomes By Tanya Kuruvilla

Connell D`Souza, alongside Team Swarthbeat, explores the cutting-edge application of EEG analysis in predicting neurological outcomes post-cardiac arrest. This blog post offers an in-depth look into the challenges and methodologies of modern medical data analysis.

Crafting the Robots of Tomorrow: The Power of Robot Simulation with MATLAB and Simulink by YJ Lim

Mihir Acharya discusses the pivotal role of MATLAB and Simulink in the future of robotics simulation. Through an engaging conversation with industry analyst George Chowdhury, this post sheds light on overcoming simulation challenges and the exciting possibilities that lie ahead.

We encourage everyone to explore these contributions further and engage with the authors and the community. Your participation is what fuels this community's continual growth and innovation.

Here's to many more discussions, discoveries, and breakthroughs together!

must-see

Highlights

Chen Lin
Last activity 2024-6-14

Run Code in Discussions Area!

We're thrilled to share an exciting update with our community: the 'Run Code' feature is now available in the Discussions area!

Simply insert your code into the editor and press the green triangle button to run it. Your code will execute using the latest MATLAB R24a version, and it supports most common toolboxes. Moreover, this innovative feature allows for the running of attached files, further enhancing its utility and flexibility.

The ‘run code’ feature was first introduced in MATLAB Answers. Encouraged by the positive feedback and at the request of our community members, we are now expanding the availability of this feature to more areas within our community.

As always, your feedback is crucial to us, so please don't hesitate to share your thoughts and experiences by leaving a comment.

General

Athanasios Paraskevopoulos
Last activity 2024-6-6

Numerical Simulation of the Discrete Klein-Gordon Equation: A Study on Damped, Driven Nonlinear Wave Systems with Spatially Extended Initial Conditions

The study of the dynamics of the discrete Klein - Gordon equation (DKG) with friction is given by the equation :

In the above equation, W describes the potential function:

to which every coupled unit

adheres. In Eq. (1), the variable $

$ is the unknown displacement of the oscillator occupying the n-th position of the lattice, and

is the discretization parameter. We denote by h the distance between the oscillators of the lattice. The chain (DKG) contains linear damping with a damping coefficient

, while

is the coefficient of the nonlinear cubic term.

For the DKG chain (1), we will consider the problem of initial-boundary values, with initial conditions

and Dirichlet boundary conditions at the boundary points

and

, that is,

Therefore, when necessary, we will use the short notation

for the one-dimensional discrete Laplacian

Now we want to investigate numerically the dynamics of the system (1)-(2)-(3). Our first aim is to conduct a numerical study of the property of Dynamic Stability of the system, which directly depends on the existence and linear stability of the branches of equilibrium points.

For the discussion of numerical results, it is also important to emphasize the role of the parameter

. By changing the time variable

, we rewrite Eq. (1) in the form

. We consider spatially extended initial conditions of the form:

where

is the distance of the grid and

is the amplitude of the initial condition

We also assume zero initial velocity:

the following graphs for

and

% Parameters
L = 200;  % Length of the system
K = 99;  % Number of spatial points
j = 2;  % Mode number
omega_d = 1;  % Characteristic frequency
beta = 1;  % Nonlinearity parameter
delta = 0.05;  % Damping coefficient
% Spatial grid
h = L / (K + 1);
n = linspace(-L/2, L/2, K+2);  % Spatial points
N = length(n);
omegaDScaled = h * omega_d;
deltaScaled = h * delta;
% Time parameters
dt = 1; % Time step
tmax = 3000; % Maximum time
tspan = 0:dt:tmax; % Time vector
% Values of amplitude 'a' to iterate over
a_values = [2, 1.95, 1.9, 1.85, 1.82];  % Modify this array as needed
% Differential equation solver function
function dYdt = odefun(~, Y, N, h, omegaDScaled, deltaScaled, beta)
    U = Y(1:N);
    Udot = Y(N+1:end);
    Uddot = zeros(size(U));
    % Laplacian (discrete second derivative)
    for k = 2:N-1
        Uddot(k) = (U(k+1) - 2 * U(k) + U(k-1)) ;
    end
    % System of equations
    dUdt = Udot;
    dUdotdt = Uddot - deltaScaled * Udot + omegaDScaled^2 * (U - beta * U.^3);
    % Pack derivatives
    dYdt = [dUdt; dUdotdt];
end
% Create a figure for subplots
figure;
% Initial plot
a_init = 2;  % Example initial amplitude for the initial condition plot
U0_init = a_init *  sin((j * pi * h * n) / L); % Initial displacement
U0_init(1) = 0; % Boundary condition at n = 0
U0_init(end) = 0; % Boundary condition at n = K+1
subplot(3, 2, 1);
plot(n, U0_init, 'r.-', 'LineWidth', 1.5, 'MarkerSize', 10); % Line and marker plot
xlabel('$x_n$', 'Interpreter', 'latex');
ylabel('$U_n$', 'Interpreter', 'latex');
title('$t=0$', 'Interpreter', 'latex');
set(gca, 'FontSize', 12, 'FontName', 'Times');
 xlim([-L/2 L/2]);
ylim([-3 3]);
grid on;
% Loop through each value of 'a' and generate the plot
for i = 1:length(a_values)
    a = a_values(i);
    % Initial conditions
    U0 = a * sin((j * pi * h * n) / L); % Initial displacement
    U0(1) = 0; % Boundary condition at n = 0
    U0(end) = 0; % Boundary condition at n = K+1
    Udot0 = zeros(size(U0)); % Initial velocity
    % Pack initial conditions
    Y0 = [U0, Udot0];
    % Solve ODE
    opts = odeset('RelTol', 1e-5, 'AbsTol', 1e-6);
    [t, Y] = ode45(@(t, Y) odefun(t, Y, N, h, omegaDScaled, deltaScaled, beta), tspan, Y0, opts);
    % Extract solutions
    U = Y(:, 1:N);
    Udot = Y(:, N+1:end);
    % Plot final displacement profile
    subplot(3, 2, i+1);
    plot(n, U(end,:), 'b.-', 'LineWidth', 1.5, 'MarkerSize', 10); % Line and marker plot
    xlabel('$x_n$', 'Interpreter', 'latex');
    ylabel('$U_n$', 'Interpreter', 'latex');
    title(['$t=3000$, $a=', num2str(a), '$'], 'Interpreter', 'latex');
    set(gca, 'FontSize', 12, 'FontName', 'Times');
      xlim([-L/2 L/2]);
ylim([-2 2]);
    grid on;
end
% Adjust layout
set(gcf, 'Position', [100, 100, 1200, 900]); % Adjust figure size as needed

Dynamics for the initial condition ,

, for

, for different amplitude values. By reducing the amplitude values, we observe the convergence to equilibrium points of different branches from

and the appearance of values

for which the solution converges to a non-linear equilibrium point

Parameters:

Detection of a stability threshold

: For

, the initial condition ,

, converges to a non-linear equilibrium point

Characteristics for

, with corresponding norm

where the dynamics appear in the first image of the third row, we observe convergence to a non-linear equilibrium point of branch

This has the same norm and the same energy as the previous case but the final state has a completely different profile. This result suggests secondary bifurcations have occurred in branch

By further reducing the amplitude, distinct values of

are discerned: 1.9, 1.85, 1.81 for which the initial condition

with norms

respectively, converges to a non-linear equilibrium point of branch

This equilibrium point has norm

and energy

. The behavior of this equilibrium is illustrated in the third row and in the first image of the third row of Figure 1, and also in the first image of the third row of Figure 2. For all the values between the aforementioned a, the initial condition

converges to geometrically different non-linear states of branch

as shown in the second image of the first row and the first image of the second row of Figure 2, for amplitudes

and

respectively.

Refference:

Dynamics of nonlinear lattices: asymptotic behavior and study of the existence and stability of tracked oscillations-Vetas Konstantinos (2018)

Highlights

Chen Lin
Last activity 2024-6-13

Introducing a New Discussions Area for Cody Users!

Many MATLAB enthusiasts come Cody to sharpen their skills, face new challenges, and engage in friendly competition. We firmly believe that learning from peers is one of the most effective ways to grow.

With this in mind, the Cody team is thrilled to unveil a new feature aimed at enriching your learning journey: the Cody Discussion Channel. This space is designed for sharing expertise, acquiring new skills, and fostering connections within our community.

On the Cody homepage, you'll now notice a Discussions section, prominently displaying the four most recent posts. For those eager to contribute, we encourage you to familiarize yourself with our posting guidelines before creating a new post. This will help maintain a constructive and valuable exchange of ideas for everyone involved.

Together, let's create an environment where every member feels empowered to share, learn, and connect.

cody

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Gareth
Last activity 2024-5-30

Podcast highlighting a popular MATLAB community Toolbox.

Check out this episode about PIVLab: https://www.buzzsprout.com/2107763/15106425

Join the conversation with William Thielicke, the developer of PIVlab, as he shares insights into the world of particle image velocimetery (PIV) and its applications. Discover how PIV accurately measures fluid velocities, non invasively revolutionising research across the industries. Delve into the development journey of PI lab, including collaborations, key features and future advancements for aerodynamic studies, explore the advanced hardware setups camera technologies, and educational prospects offered by PIVlab, for enhanced fluid velocity measurements. If you are interested in the hardware he speaks of check out the company: Optolution.

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Oleksandr
Last activity 2024-5-28

Pricing and Licensing

Let's talk about probability theory in Matlab.

Conditions of the problem - how many more letters do I need to write to the sales department to get an answer?

To get closer to the problem, I need to buy a license under a contract. Maybe sometimes there are responsible employees sitting here who will give me an answer.

Thank you

Highlights

David
Last activity 2024-5-28

Week of May 27th - Must-See MATLAB Central Posts

Hello MATLAB Community!

We've had an exciting few weeks filled with insightful discussions, innovative tools, and engaging blog posts from our vibrant community. Here's a highlight of some noteworthy contributions that have sparked interest and inspired us all. Let's dive in!