I have tried to make a loop where it displays all the answers in a matrix but it doesn't give me the 21x3 matrix. Am i using wrong commands or am i missing something.

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merlin kelly
merlin kelly 2018-11-14
评论： Luna 2018-11-15
t=0;
for v=[t,sin(t),cos(t)]
if t<21
disp(v)
t=t+1;
end
end

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Luna
Luna 2018-11-14
Hi Merlin,
try this code below:
v = [];
for t = 0:1:20
v(t+1,:) = [t,sin(t),cos(t)] ;
end
  2 个评论
merlin kelly
merlin kelly 2018-11-14
Thank you this was very helpful, what happens when v = [ ];, shouldn't i write down v=[t,sin(t),cos(t)] or will that not work
Luna
Luna 2018-11-15
actually I prefer to define v = nan(21,3). Pre-allocation of the size increases the performance, and speed up the for loop.
defining empty ( v = [] ) is something about usage.
For example: if you use your for loop in if-else block, defining empty in the beginning helps you understand whether it goes to if or else block, etc.
You can easily check if isempty(v) that your matrix filled with values or remained empty at end of the process.

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