how to reference previous value of function?

I am trying to write a function that depends on its own previous value and the previous value of another variable.

Below is the code I am working on:

Storage, where Smax=100; k=0.3

TimeDay = 1:1088;
TimeDay = TimeDay';
K=0.3;
Storage = 0;

for i = 1:1088
      Storage(end+1) = (1-K)*((Storage(end)) + (Precipmmday(end)));
end
Storage = Storage';
TimeDay = 1:1089;
plot (TimeDay, Storage)

The output is incorrect. I've tried a lot of ideas for editing it but can't figure it out. Any help appreciated!

I did it correctly in excel (attached). Also attached is the data file.

Answer 1

[Star Strider]

This seems to work:

fidi = fopen('A1Rainfalldata.txt');
R = textscan(fidi, '%d %f', 'HeaderLines',1);
Precipmmday = cell2mat(R(:,2));
K = 0.3;
Storage = [Precipmmday(1) 0 0];
for k1 = 2:length(Precipmmday)
    Storage(k1,:) = [Precipmmday(k1) (Storage(k1-1,2)+Precipmmday(k1-1))*(1-K)  (Storage(k1-1,2)+Precipmmday(k1-1))*K];
end

The ‘Storage’ array matches your Excel output.

[Vert]

Thank you so much, I really appreciate it. Someday when I am competent in MatLab I will remember to help people learn!

[Star Strider]

My pleasure!

If I solved your problem, please Accept my answer.