Size of a matrix after conditions is incorrect.

I am writing a loop with conditionals. But, I have an error in the calculation, about the size of a matrix.

This is my minimal code:

clc; clear all; close all;
t = 7.71; % mm
h = 50;

d = h - 2*t;
yel = .01*d:1:h/2;

for i = 1:length(yel)
    if yel(i) < d/2
    Mt1(1:i) =  2+yel(i);
    end
end

for i = 1:length(yel)
    if yel(i) > d/2
    Mt2(i) = 3-yel(i);
    end
end

Mt1
Mt2

The Mt1 and Mt2 matrices should have the same length. I have operate step by step in the Command Window, and it is all right.

Why is the length different if I have the same logic condition when I use if?

I tried to fix it but I couldn't. I hope you help me.

PD. I don't have much experience in Matlab.

[Isai Fernandez]

For my purposes, I finally solve it:

 Mt = (yel < d/2).*(2+yel) + (yel > d/2).*(3-yel);

Instead of conditionals if and loop for.

Answer 1

[Steven Lord]

The last element of yel may be greater than d/2, may be less than d/2, or may be neither greater than nor less than d/2. It can't be both greater than d/2 AND less than d/2 simultaneously. So you can't assign to both element length(yel) of Mt1 and element length(yel) of Mt2. They may be the same length if you assign to element length(yel) of neither Mt1 nor Mt2 (if yel(end) is exactly equal to d/2 or is NaN) but usually one will end up at least one element longer than the other.

[Isai Fernandez]

I don't get it, I operate manually, and the logic matrices are ready to be used, with the required lengths and values.

Do I must change the yel matrix?

i = 1:length(yel)

i =

Columns 1 through 13

     1     2     3     4     5     6     7     8     9    10    11    12    13

Columns 14 through 25

    14    15    16    17    18    19    20    21    22    23    24    25
 >> yel(i) < d/2

ans =

1×25 logical array

Columns 1 through 19

   1   1   1   1   1   1   1   1   1   1   1   1   1   1   1   1   1   0   0

Columns 20 through 25

   0   0   0   0   0   0

>> yel(i) > d/2

ans =

1×25 logical array

Columns 1 through 19

   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   1   1

Columns 20 through 25

   1   1   1   1   1   1