Effacer les filtres
Effacer les filtres

solving two-variable matrix function

3 vues (au cours des 30 derniers jours)
Dmitry Solomatin
Dmitry Solomatin le 14 Déc 2022
Commenté : Jiri Hajek le 14 Déc 2022
Hi,
so assume I have a function like this:
f = [x(1) + x(2) ; x(2) * x(1)]
and my x = [2; -2]
how can I solve it? feval doesnt work for some reason ("Dimensions of arrays being concatenated are not consistent)

Réponses (1)

Jiri Hajek
Jiri Hajek le 14 Déc 2022
Hi this can be done using inline function very efficiently like this:
fh=@(x,y)[x+y,x*y];
fh(2,-2)
ans = 1×2
0 -4
  2 commentaires
Dmitry Solomatin
Dmitry Solomatin le 14 Déc 2022
Thanks it now works, but for some reason this gives me a 1x3 matrix and it should only 1x2?
fh = @ (x,y) [2*x- 400*x*(-x^2+y) -2, 200 * (y-x^2)];
fh(2,-2)
Jiri Hajek
Jiri Hajek le 14 Déc 2022
This is because Matlab interprets space within brackets as a separator of vector elements, same as a comma. You can eithertake away all the spaces or put your expressions into parentheses. That way, you can forget about the meaning of spaces:
fh = @ (x,y) [(2*x- 400*x*(-x^2+y) -2), (200 * (y-x^2))]
fh = function_handle with value:
@(x,y)[(2*x-400*x*(-x^2+y)-2),(200*(y-x^2))]
fh(2,-2)
ans = 1×2
4802 -1200

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