MATLAB: How to modify the 1D random walk sequence to a reflecting type random walk

random walk

I have a sequence 'x' generated as below (for simulating 1D random walk):

r=rand(1,1000);
r(r>.5)=1;
r(r<=.5)=-1;
x=cumsum(r);

If I consider 2 values in the sequence , say +10 and -10, then I would like to reflect the sequence 'x' when it reaches those values. How to achieve this?

Best Answer

Try this

logicalIndexes = x > 10
x(logicalIndexes) = 10 - x(logicalIndexes);
logicalIndexes = x < -10
x(logicalIndexes) = -10 - x(logicalIndexes);

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MATLAB: I am brand new to MATLab and do not know how to do a whileloop

Lots of errors - too many to list. Just study corrected code:

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 25;
fig=figure(1);
x(1)=0;
fx(1) = 0;
index = 2;
while (x<20) & index < 1000 % Add index check as a failsafe.
  x(index)=x(index-1)+0.5
  fx(index)= x(index)^3 - (5*x(index))^2 + 2^(x(index)) - 10000.*x(index);
  clf;
  grid on;
  hold on;
  xlabel('x', 'FontSize', fontSize); 
  ylabel('fx', 'FontSize', fontSize); 
  title('While Loop', 'FontSize', fontSize);
  p = plot(x, fx, 'ro-', 'LineWidth',2, 'MarkerSize', 10);
  index = index + 1;
end
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0 0 1 1]);

Of course I hope you know you could do this without a while loop in just a few lines, but I guess you were interested in the while loop mechanics rather than just how to plot a curve.

MATLAB: Random walk problem.

This looks like homework and many people uploading homework problems edit them away after they've been answered. We will be sure to not to do majority of work (so you won't be cheating) if you promise not to delete the question after we help you.

Hint: Basically you might do something like

if x+deltaX > xMax
    x = xMax - (x + deltaX - xMax); % Reflect about xMax
end

Best Answer

Related Solutions

MATLAB: I am brand new to MATLab and do not know how to do a whileloop

MATLAB: Random walk problem.

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