How to build onto a matrix/vector in Simulink

I'm writing a function in Simulink as part of a simulation of galaxies that extracts velocity and position data and such. I have the outputs of the functions I used to arrive at that the outputs, which are scalars. I was trying to make a function that loads a matrix or vector and adds a new column every time I run a new simulation so I don't have to manually record the data at each interval. It uses the "from file" for input and "to file" for the output. I set the file initially to a vector of zeros. The code looks like this in the function.

function partoutput = particleadd(particles,x,partoutput)
partoutput(x) = particles
end

Particles is a scalar value that I have as an input. x is the iteration I am on, which is just an input block, and partoutput is the vector I am trying to add on to. When I run it, it gives me this error:

"Simulink does not support loading the input data in file 'partoutput.mat'. For data saved using MAT file versions prior to 7.3, Simulink can only load two-dimensional arrays consisting of one-dimensional, double, noncomplex samples. To load data of any other type, complexity or dimension, use a timeseries object and save the file using MAT file version 7.3 or later. For example, use: 'save file_name -v7.3 timeseries_object'."

The array is not three dimensional, and that code does not work that it suggest.

[Birdman]

Can you share your model with all necessary variables?

[Nhan Ngo]

Dropbox

In the folder should be all you need. I'm using MATLAB R2017a and Simulink 8.9. The simulation looks like a mess but all you have to worry about is the function in the upper right corner. If you delete that function you can see what the output looks like.

Thanks.