Hello!

I would like to ask for your help on how to open a text file in scilab and placing its elements in an array, so that I can plot the elements and calculate its mean-squared displacement.

The data in the text file looks like this:

===start of file===

3
1
1
17
2
2
14
1
2
3

# and so on...

====end of file====

The data points for the plot look like this: (x-val, y-val) or

[(1,3),(2,1),(3,1),(4,17),(5,2),(6,2),(7,14),(8,1),(9,2),(10,3),...]

where x-val are just counting numbers 1,2,3,4,5,... and y-val are the elements of the input file.

Also, using the same input file, the mean-squared displacement is calculated like this (matlab code):

===start of matlab codes===

nData = size(data,1); %# number of data points
numberOfdeltaT = floor(nData/4); %# for MSD, dt should be up to 1/4 of number of data points

msd = zeros(numberOfDeltaT,3); %# We'll store [mean, std, n]

%# calculate msd for all deltaT's

for dt = 1:numberOfDeltaT
   deltaCoords = data(1+dt:end,2:4) - data(1:end-dt,2:4);
   squaredDisplacement = sum(deltaCoords.^2,2); %# dx^2+dy^2+dz^2

   msd(dt,1) = mean(squaredDisplacement); %# average
   msd(dt,2) = std(squaredDisplacement); %# std
   msd(dt,3) = length(squaredDisplacement); %# n
end

====endof matlab codes====

Given this code, how do we plot msd (y-axis) vs deltaT (x-axis)?

I appreciate all your help. Thank you!