Is vectorizing this even possible?
显示 更早的评论
vec3(1) = 1;
i = 1;
while i<5
i = i+1;
vec3(i) = (vec3(i-1)+2)^2;
end
vec3
采纳的回答
Walter Roberson
2020-9-17
I posted the complete vectorization several days ago; . Unfortunately the person deleted the question.
syms v v0 c
f(v) = (v+c)^2;
f5 = f(f(f(f(f(v0)))));
vec3_5 = expand(subs(f5, c, 2));
v0^32 + 64*v0^31 + 2016*v0^30 + 41600*v0^29 + 631536*v0^28 + 7511168*v0^27 + 72782528*v0^26 + 590011136*v0^25 + 4077667064*v0^24 + 24363708032*v0^23 + 127184607424*v0^22 + 584772138240*v0^21 + 2382767071968*v0^20 + 8644745151232*v0^19 + 28021844462720*v0^18 + 81349497514496*v0^17 + 211814884610908*v0^16 + 494935571753856*v0^15 + 1037540400943680*v0^14 + 1949025086827264*v0^13 + 3273934344609568*v0^12 + 4902203714779904*v0^11 + 6514485357242496*v0^10 + 7638211784159744*v0^9 + 7840967227104336*v0^8 + 6975721989473536*v0^7 + 5305860461727104*v0^6 + 3387252771621376*v0^5 + 1768336935606208*v0^4 + 726328276999680*v0^3 + 220554340195584*v0^2 + 44118436709376*v0 + 4371938082724
Where v0 = 1
3 个评论
Bruno Luong
2020-9-17
Very uggly, but admitly it answers the question.
Walter Roberson
2020-9-18
Yup ;-)
Using a for loop is not vectorizing . This solution is not vectorized in terms of the number of iterations, but it is vectorized in terms of different initial conditions.
I think it should be possible to calculate what all the terms should be, in terms of binomial coefficients and number of iterations, but the form is not coming to mind immediately.
Payton Brown
2020-9-18
更多回答（1 个）
madhan ravi
2020-9-17
编辑：madhan ravi
2020-9-17
A simple for loop is the best and easier to understand:
vec3 = zeros(5,1);
vec3(1) = 1;
for k = 2:5 % edited after Stephen’s comment
vec3(k) = (vec3(k-1)+2)^2;
end
vec3
2 个评论
Stephen23
2020-9-17
Starting the for loop from one will throw an error. Better to start from two:
vec3 = ones(5,1);
for k = 2:5
vec3(k) = (vec3(k-1)+2)^2;
end
madhan ravi
2020-9-17
Ah thanks Stephen!
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