Building a matrix with a for-loop

Hello, I am constructing a matrix using the following program:

%Program HW13.m
x = 35;
y = 26;
n = 5;
for i = 1:1:n+1
  x(i+1) = 18*x(i) - 11*y(i);
  y(i+1) = 8*x(i) - y(i);
end

The for-loop generates two matrices, one for "x" and one for "y". However, I need to create new matrix: column 1 with the "i" values, column 2 with the iterated "x" values, column 3 with the iterated "y" values, and column 4 with "x/y" values. Any suggestions on how to do this?

Answer 1

[Walter Roberson]

[(1:n+1).', x(:), y(:), x(:)./y(:)]

[Viktoria Kolpacoff]

Tried this command; however it says that the dimensions are not consistent.

[Star Strider]

That should be:

[(1:n+2).', x(:), y(:), x(:)./y(:)]

because of the way the indices work, so the number of elements is n+1+1.

Answer 2

[Andrei Bobrov]

n = 5;
out = zeros(n+2,4);
out(1,2) = 35;
out(1,3) = 26;
for ii = 1:n+1
    out(ii+1,2) = 18*out(ii,2) - 11*out(ii,3);
    out(ii+1,3) = 8*out(ii,2) - out(ii,3);
end
out(:,1) = 1:n+2;
out(:,end) = out(:,2)./out(:,3);

[Viktoria Kolpacoff]

Thank you for your help. However, when I run the program, I get:

out =

   1.0e+07 *

    0.0000    0.0000    0.0000    0.0000
    0.0000    0.0000    0.0000    0.0000
    0.0000    0.0003    0.0002    0.0000
    0.0000    0.0034    0.0025    0.0000
    0.0000    0.0335    0.0245    0.0000
    0.0000    0.3334    0.2434    0.0000
    0.0000    3.3235    2.4235    0.0000

[Andrei Bobrov]

>> format short g
>> out
out =
            1           35           26       1.3462
            2          344          254       1.3543
            3         3398         2498       1.3603
            4        33686        24686       1.3646
            5    3.348e+05    2.448e+05       1.3676
            6   3.3336e+06   2.4336e+06       1.3698
            7   3.3235e+07   2.4235e+07       1.3714

[Stephen23]

@Viktoria Kolpacoff: what is the problem with that output? Remember that the factor 1.0e+07 * applies to all elements of the displayed array. You can use format to change how output is displayed in the command window.