What is the meaning of 'internal sorting rules' in 'sort' in Symbolic Math Toolbox?

A = [factorial(sym(1001)), exp(sym(1)) + factorial(sym(1000))]
[r,s] = sort(A)

Obviously, A(1) > A(2). However, the output is

r =

[factorial(1001), exp(1) + factorial(1000)]

s =

1 2

which is quite confusing.

I notice in sort, it is mentioned that

• If X contains symbolic irrational numbers, expressions, and functions, comparing and sorting the elements can be computationally complex. Therefore, sort uses internal sorting rules to optimize its performance.

What is the meaning of 'internal sorting rules' ?

Thank you very much!

Answer 1

[David Hill]

A = [factorial(sym(1001)), exp(sym(1)) + factorial(sym(1000))]
[~,s] = sort(vpa(A));%vpa the symbolic before sorting.
A=A(s);%sorted symbolic

[Songbai Jin]

Thank you for your answer!

But my original idea is to prevent a 'vpa' method.

Is it possible to sort sym variables directly?

Thank you for your answering anyway!