Creating matrix nested for loop

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Detox
Detox 2016-10-22
评论： Jan 2016-10-24
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?
Thanks in advance!
  1 个评论
Jan
Jan 2016-10-24
@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.

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回答（1 个）

Chaya N
Chaya N 2016-10-22
编辑：Chaya N 2016-10-22
If you already have all these data available (in separate vectors, I assume) then you do not need any loops.
For example, if you had
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!
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Chaya N
Chaya N 2016-10-22
If you still have trouble, please also include your equation for y(t) when you post here.
Detox
Detox 2016-10-24
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;

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