MATLAB Answers

## Average trajectory of multiple 2D random walk trajectories

Asked by Kelly McGuire

### Kelly McGuire (view profile)

on 15 Jan 2019
Latest activity Edited by Kelly McGuire

### Kelly McGuire (view profile)

on 15 Jan 2019
How would I plot the average trajectory of multiple 2D random walk traces constrained between two points? Here is the code I am using:
clc
clear all
%Ask for number of rivers
NumberOfSimulations = input('How many rivers? \n');
%Ask for number of steps
n = input('How many steps? \n'); % number of steps, nt increasing and n(t-1) decreasing
%StartPoint
x0=0;
%End point after n steps
xtarg=40;
Saved=NaN*zeros(n+1,NumberOfSimulations+2); %Initializes Array
Saved(1,:)=x0; %Fills first row with x0 value
Saved(n+2,:)=xtarg; %Fills last row with xtarg value
for q = 1:NumberOfSimulations
unifs = rand(n+1,1);
x = x0;
for i = 0:(n-1)
t = (1-(xtarg-x)/(n-i))/2;
if unifs(i+1,1) <= t
x = x-1;
else
x = x+1;
end
Saved(i+2,q) = x;
end
end
figure(1);
hold on;
plot(Saved);
plot(mean(Saved,2),'k','Linewidth',2.5);

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