Random Walk Simulation for Multiple Particles

Question

Will Jeter 2021-2-4

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/735572-random-walk-simulation-for-multiple-particles

回答： Alan Stevens 2021-2-4

Im trying to perform a randown walk for 1000 particles, simuating each for 20 steps. Im then supposed to calcualte and plot the mean square displacement but im not sure how. Here's what i have so far...

% Simulation of a random walk (delta = 1, tau = 1)
rng('Shuffle')                         
nSteps = 20;                          
positionArray = zeros(nSteps+1, 1);     
stepNumber = 0:nSteps;                  
position = 0;                          
for index = 1:nSteps
    randomMove = rand;                  % random number between 0 and 1; used to decide direction of random move
    if (randomMove <= 0.5)
        position = position+1;          % move right
    else
        position = position-1;          % move left
    end
    
    positionArray(index+1) = position;  % store position
end
plot(stepNumber,positionArray,'k')      % plot the position as a function of step number
set(gca,'FontSize',10);
xlabel('number of steps','FontSize',10)
ylabel('position','FontSize',10)

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Answer 1

Alan Stevens 2021-2-4

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/735572-random-walk-simulation-for-multiple-particles#answer_614592

在 MATLAB Online 中打开

Do you mean like this:

% Simulation of a random walk (delta = 1, tau = 1)
rng('Shuffle')                         
trials = 1000;
nSteps = 20;                          
positionArray = zeros(nSteps+1, 1);     
stepNumber = 0:nSteps;    
meansquaredisplacement = zeros(trials,1);
for trial = 1:trials
    squareposn = 0;
    position = 0;                          
    for index = 1:nSteps
        randomMove = rand;                  % random number between 0 and 1; used to decide direction of random move
        if (randomMove <= 0.5)
            position = position+1;          % move right
        else
            position = position-1;          % move left
        end
    end
    squareposn = squareposn + position^2;
    meansquaredisplacement(trial) = squareposn/nSteps;
end
 
plot(1:trials,meansquaredisplacement,'k')      % plot the msd as a function of step number
set(gca,'FontSize',10);
xlabel('trial','FontSize',10)
ylabel('mean square displacement','FontSize',10)