# appending element to vector

8 visualizaciones (últimos 30 días)
shobhit mehrotra el 4 de Feb. de 2015
Comentada: Guillaume el 4 de Feb. de 2015
Hello Im a diff function to estimate a derivative(du/dx), however I lose an element as excepted, now I want to add the average value of the derivative to the end of vector (du/dx) such that is the same length as u. Thanks
##### 0 comentariosMostrar -2 comentarios más antiguosOcultar -2 comentarios más antiguos

Iniciar sesión para comentar.

### Respuestas (2)

Guillaume el 4 de Feb. de 2015
That doesn't sound very sensible as you're mixing two different entities into a single variable, but if that's what you want to do:
x = sin(linspace(0, pi, 100)); %for example
d = diff(x);
dwithmean = [d mean(d)]
##### 2 comentariosMostrar NingunoOcultar Ninguno
shobhit mehrotra el 4 de Feb. de 2015
i have this script
for n = 1:length(dataind)
winddivergencex(n)= (diff(Ui(min(dataind{n}): (max(dataind{n})))))./(diff(longm(min(dataind{n}):(max(dataind{n})))));
winddivergencex has to contain the same number of elements as n so i want append a term to the end of the winddivergencex vector so they have the same amount of elements. Thanks
Guillaume el 4 de Feb. de 2015
Why do they have to have the same number of elements?

Iniciar sesión para comentar.

Michael Haderlein el 4 de Feb. de 2015
As Guillaume has mentioned, that's not the usual way to go. Assume you want to plot the data (which requires equally sized arrays), these are the common options:
x=linspace(0,100);
y=x.^2;
dydx=diff(y)./diff(x);
figure, hold all
%best way: shift the x by half dx
x2=x(1:end-1)+diff(x)/2;
plot(x2,dydx)
%lazy way: just use n-1 x values
plot(x(1:end-1),dydx)
%semi-lazy way: add nan (will not be plotted)
dydx=[diff(y)./diff(x) nan];
plot(x,dydx)
When you run these lines, you see a shift between the blue line (which is technically correct) and the red/green lines (overlaying).
##### 0 comentariosMostrar -2 comentarios más antiguosOcultar -2 comentarios más antiguos

Iniciar sesión para comentar.

### Categorías

Más información sobre Logical en Help Center y File Exchange.

### Community Treasure Hunt

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

Start Hunting!

Translated by