Replace powers with a sequence
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Mohammad Shojaei Arani
am 26 Jan. 2022
Kommentiert: Mohammad Shojaei Arani
am 27 Jan. 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 Kommentare
Rik
am 26 Jan. 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.
Antworten (1)
Torsten
am 26 Jan. 2022
syms x
c = sym2poly(expand((x-1)^3));
e = sym('e',[3,1]);
c_times_e = c*e
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