# Creating 3x201 matrix from set of numbers

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chesapeakedipper on 7 Jul 2020
Hi all,
I apologize in advance but I'm a newbie and don't have much experience with matlab - anyway here's what I'm trying to do.
I want to build a 201x3 matrix where every row has the same numbers, and the numbers in the columns go from 0 to 20e-10 with steps of 0.1e-10.
The matrix should look something like this:
[0 0 0
0.1 0.1 0.1
...
20 20 20]
I tried doing this by nesting three "for" loops in the following way:
for i = 0:0.1e-10:20e-10
for j = 0:0.1e-10:20e-10
for k = 0:0.1e-10:20e-10
I = [i,j,k];
end
end
end
but instead of obtaining 201x1 vectors, i, j and k are just numbers (20e-10, to be precise).
I tried looking into other commands but I've been asked to do this specifically with nested for loops.
Sorry in advance if it's a silly question - and thanks to whoever takes the time to help!

KLR on 7 Jul 2020
Matt's answer is the most efficient. However since you mentioned you needed to do it specifically with for loops here's the code that will do it in a nested loop.. One thing I noticed in your loop was that your variable I was being overwritten by the latest value of i,j,k hence all you were seeing was the last value of i,j,k.
Matrix=zeros(201,3);
for i=1:1:200
for j=1:1:200
for k=1:1:200
I=i/10;
Matrix(i+1,:)=I;
end
end
end

#### 1 Comment

chesapeakedipper on 7 Jul 2020
thanks, this is great :)

Matt J on 7 Jul 2020
I=(0:0.1e-10:20e-10).' *[1,1,1];

#### 1 Comment

chesapeakedipper on 7 Jul 2020
way simpler than what i tried - thanks a lot :)