For Loop, Unequal Sizes Help

Hello,

I am having trouble with a loop. When I do the calculation using only one iteration it seems to work perfecty, but as soon as I try inputting it as a loop and changing the corresponding values the loop fails. Any ideas or help is greatly appreciated. The first part of the code is just to set it up the problem.

load('boulder.mat')
b_droptime = droptime;
b_t = t;
b_y = y;
 
b_dydyo = ones(631,186);
 b_dydvo = b_t;
 b_dydg = 0.5*(b_t.^2);
 W = eye(631);
 
  X = zeros(186,3);
for c = 1:186
    H = [b_dydyo(:,c), b_dydvo(:,c), b_dydg(:,c)];
    Y = b_y(:,c);
    X(c,:) = (((H.')*W*H)\((H.')*W*Y));
end

This is the part of the code I am struggling with below

 theo_y_B = zeros(631,186);
 for up = 1:186
theo_y_B(up) = X(up,1) + X(up,2) * b_t(:,up) + 0.5 * X(up,3) * b_t(:,up).^2;
end

Whereas if I do just

theo_y_B = X(1,1) + X(1,2) * b_t(:,1) + 0.5 * X(1,3) * b_t(:,1).^2;

it works.

What do I not understand about "for loops"?

Answer 1

[Ameer Hamza]

Change the line

from

theo_y_B(up) = X(up,1) + X(up,2) * b_t(:,up) + 0.5 * X(up,3) * b_t(:,up).^2;

to

theo_y_B(:, up) = X(up,1) + X(up,2) * b_t(:,up) + 0.5 * X(up,3) * b_t(:,up).^2;

See more about array indexing here: https://www.mathworks.com/help/matlab/math/array-indexing.html

[Ryan Griffith]

Thank you

[Ameer Hamza]

I am glad to be of help!