Adding matric to an empty matric

Hello,

I have an empty matrix

em = [];

I also have other matrices x1, x2 and x3;

t = 0:1/32798:0.25-1/32798;

x1 = sin(2*pi*1356*t) + sin(2*pi*297*t);

x2 = sin(2*pi*3336*t) + sin(2*pi*997*t);

x3 = sin(2*pi*2336*t) + sin(2*pi*497*t);

I would like to add x1, x2, and x3 into em.

since x1, x2 and x3 are 1 x 8199. I would like to put x1 in row1, x2 in row 2 and x3 in row 3.

How do I do this?

Thank you.

Answer 1

[Matt J]

 em=[x1;x2;x3]

or

 em=vertcat(x1, x2, x3)

or

em = cat(1,x1,x2,x3);

[kyin gab]

I was about to modify my question when I saw you have already answered it.

Well, I meant to say how can I add to em using a for loop. That is for the first iteration of the for loop,x1 wiil be added then for the second, x2 will be added.

Thanks.

[Matt J]

 em=zeros(3, 8199); %pre-allocate!!!
 newrows=[x1;x2;x3];

 for i=1:3

   em(i,:)=newrows(i,:);

 end

[kyin gab]

ok it worked. If I want to plot them against t on the same graph how will I do it?

plot(t,em); ?

[Matt J]

   plot(t, x1,t, x2,t,x3)

[kyin gab]

I want to plot them from em. This is because I will be using a for loop to enter the values of em and the size is not fixed.

[Matt J]

 args=[repmat({t},size(em,1),1),  num2cell(em,2)].';
 plot(args{:});