How can I create a matrix from the values of a For loop?

I want to creat a matrix of 2 columns and the obtained rows after doing a for and if loops. I only want to create the matrix when the value of x2 pass the if condition. In this way, I want to get the x2 values on the first column and the b values on the second one. And not overwrite in the before value. I dont know how to do it. I would appreciate your help.

This is my code:

b=
0
0,510000000000000
1,02000000000000
1,53000000000000
2,03000000000000
2,54000000000000
-0,510000000000000
-1,02000000000000
-1,53000000000000
-2,54000000000000
-2,03000000000000
-3,04000000000000

alpha=10;
m=tand(alpha);
c=-40:1:3; %x-en mobitu bidana
y0=-3.5;
y1=3.5;
k=1;
h=1;
x2=zeros(size(CoordX));
matrix=zeros(size(CoordX),2);

for i=1:1:length(c)
n=y0-m*c(i);
x1=(y1-n)/m;
plot([c(i) x1],[y0 y1],'r');
for j=1:1:length(b)
x2(k)=(b(j)-n)/m;
scatter(x2(k),b(j),'g');
if x2(k)>posX_min && x2(k)<posX_max
matrix(:,h)=[x2(k) b(j)];
j=j+1;
k=k+1;
h=h+1;
end
end
i=i+1;
end

Answer 1

[Nut]

Hi,

I'm not sure, but I think you can try this (I refer to the first version of code that you wrote):

matrix = [];
for j=1:1:length(b)
    x2(k)=(b(j)-n)/m;
    scatter(x2(k),b(j),'g');
    if x2(k)>posX_min && x2(k)<posX_max
        matrix(size(matrix,1)+1,:) = [x2(k) b(j)];
        k=k+1;
    end
    j=j+1;
end