# Creating matrix nested for loop

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Detox on 22 Oct 2016
Commented: Jan on 24 Oct 2016
I need to write a matrix where the first column has the varying mass of an ODE, the second to n-th column all the y(t) values of that ODE. I tried to solve this with a nested for loop but somehow fail so hard eventhough I am sure it is pretty easy.
for row_index = 1:10
for col_index = 1:length(time)
Matrix(row_index,column_index) = [mass(row_index)];
end
end
Somehow something after "[mass(row_index)]" is missing or do you know a way to make it more elegant?
Jan on 24 Oct 2016
@Detox: Please do not cross-post a question. If it is really important to post a question in different forums, please add at least links to the other forum. Otherwise the voluntary helpers waste time with writing answers, which have been given elsewhere already. Thanks.

Chaya N on 22 Oct 2016
Edited: Chaya N on 22 Oct 2016
If you already have all these data available (in separate vectors, I assume) then you do not need any loops.
x = [all the ODE mass values];
y1 = [values for y(1)]; % at time = 1
y2 = [values for y(2)]; % at time = 2
.
.
.
yt = [values for y(t)]; % at some time 't'
you could do:
matrix = [x y1 y2 ... yt]; if all of these are column vectors and of the same length
or
matrix = [x; y1; y2; ...; yt]'; if all of these are row vectors of the same length
NOTE: Please observe the differences in syntax between the two versions!
Detox on 24 Oct 2016
Function is:
function ydot = Exp_01(t,y,m)
ydot = zeros(size(y));
ydot(1) = y(2);
ydot(2) = (-y(2)-100*y(1))./m;