How to create a vector of symbolic variables with specific labeling

1 回表示 (過去 30 日間)
KostasK
KostasK 2021 年 9 月 12 日
回答済み: John D'Errico 2021 年 9 月 12 日
I currently have a vector of unevenly spaced increasing values similar to this one:
v = [1 2 3 5 7 9 10 12 18 29]
What I would like to do is create a vector of symbolic variables such that
vsym = [x1 x2 x3 x5 x7 x9 x10 x12 x18 x29]
I know that I can create a function to produce symbolic variables with increasing indices from 1 to 10 lets say by using sym('x', [1 10]), however I am not able to find a way to quickly assign them different indices as I would desire, such as sym('x', v), whee v would be my vector.
Any help would be appreciated

採用された回答

Paul
Paul 2021 年 9 月 12 日
v = [1 2 3 5 7 9 10 12 18 29];
vsym = sym('x',[v(1) v(end)]);
vsym=vsym(v)
vsym = 
  2 件のコメント
Awais Saeed
Awais Saeed 2021 年 9 月 12 日
編集済み: Awais Saeed 2021 年 9 月 12 日
It will only work if vector v starts from 1. If vector v starts from 2, let's say, then the results would be different because the syntax requires rows and columns as sym('x', [rows columns]).
v = [2 3 5 7 9 10 12 18 29];
vsym = sym('x',[v(1) v(end)]);
vsym=vsym(v)
vsym = 
Paul
Paul 2021 年 9 月 12 日
v = [2 3 5 7 9 10 12 18 29];
vsym = sym('x',[1 v(end)]);
vsym = vsym(v)
vsym = 

サインインしてコメントする。

その他の回答 (2 件)

Awais Saeed
Awais Saeed 2021 年 9 月 12 日
Not the best way but will work good enough for small vectors
vsym = sym('x',size(v));
for col = 1:1:size(v,2)
char_str = ['x' num2str(v(col))];
vsym(col) = sym(char_str);
end
disp(vsym)
I do not know if this could be done more faster.

John D'Errico
John D'Errico 2021 年 9 月 12 日
The simple direct way seems easiest.
v = sym('v',[1 29]);
v = v([1 2 3 5 7 9 10 12 18 29])
v = 

カテゴリ

Help Center および File ExchangeCreating and Concatenating Matrices についてさらに検索

Community Treasure Hunt

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

Start Hunting!

Translated by