Replace powers with a sequence

1 visualización (últimos 30 días)
Mohammad Shojaei Arani
Mohammad Shojaei Arani el 26 de En. de 2022
Comentada: Mohammad Shojaei Arani el 27 de En. de 2022
Hello friends!
Consider a binomial symbolic expression like (x-1)^3 and a symbolic vector e of size 3 (e=sym('e',[1 3]) ). Of
course, in my real problem I have 'n' instead of 3 but I just used 3 here for simplicity. If expand (x-1)^3 then I get
(x-1)^3 = x^3-3*x^3+3*x-1;
which includes all powers of x from 0 to 3, as we know. Now, I need to substitute x with e(1), x^2 with e(2), x^3 with e(3).
Unfortunately, I cannot use 'subs' command here since when I try to assign x with e(1), it automatically assigns x^2 with
e(1)^2 and x^3 with e(1)^3 which is not what I want (similarly, if I try to asign x^2 with e(2) it might interfere with other powers
of x).
Ant idea?
Thanks!
Babak
  2 comentarios
Rik
Rik el 26 de En. de 2022
If by e(k) you mean exp(k), isn't the replacement equivalent to what you want? It might not look tidy, but it is the same number.
Mohammad Shojaei Arani
Mohammad Shojaei Arani el 27 de En. de 2022
No. I do not mean exp. 'e' is just a symbolic array. If you look at the title of mt post "Replace powers with asequence" you will see that I am not cconsidering a specific sequence.

Iniciar sesión para comentar.

Respuestas (1)

Torsten
Torsten el 26 de En. de 2022
syms x
c = sym2poly(expand((x-1)^3));
e = sym('e',[3,1]);
c_times_e = c*e

Categorías

Más información sobre Formula Manipulation and Simplification 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