How do I save values in my loop as a column vector?

66 visualizaciones (últimos 30 días)
Francesca Maher
Francesca Maher el 30 de Mzo. de 2020
Comentada: Francesca Maher el 30 de Mzo. de 2020
I have a loop and I need to save two values (h and err_max) from it into a column vector so that I can make a table. I have been using ' after the variable to transpose the vector so that my table works, but this sometimes causes issues when running the whole file because of other sections i have written. Is there a way to save values from a loop into a column vector without using '?
Side note: My value sol2 saves as a column vector by using sol2(k, : ) but I have tried this on h and it creates a big matrix instead.
I will copy my code here:
for i = 1:16
h = 2^-(i+1);
N = 4/h;
% Initialise variables
k = 0;
sol2 = 0;
for t = 0:h:4
k = k + 1;
sol2(k,:) = 2*(t) - exp(t);
end
w=Euler(a,b,N,alpha,f);
err_ = sol2 - w;
err_abs = abs(err_);
err_max(i) = max(err_abs);
h1(i) = h;
end
table(h1', err_max')
  1 comentario
Francesca Maher
Francesca Maher el 30 de Mzo. de 2020
Also, just to add: my code isn't running correctly at the moment for err_max

Iniciar sesión para comentar.

Respuesta aceptada

Robert
Robert el 30 de Mzo. de 2020
You can define the variables as columns before your for-loop:
h1 = zeros(16, 1);
err_max = zeros(16, 1);
By then assigning values to it, the variables remain columns.

Más respuestas (1)

Peng Li
Peng Li el 30 de Mzo. de 2020
You can use h1(:) instead to make hi1 explicitely a column vector. This has a potential risk too if you h1 is actually a matrix as it will force it to reshape to a column vector.
For your code, what is your w like? no idea about your a, b, alpha, f variables.
Your outerloop is not necessary and can be optimized. Or at least, to improve efficiency, you'd better reallocate space for those variables that change size with loop.

Categorías

Más información sobre Loops and Conditional Statements en Help Center y File Exchange.

Etiquetas

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by