Why symvar() sort 10 smaller than 9

My variables is X = X1 X2 ... X9 X10,but when I use symvar(X),I get X1 X10 X2 ... X9。

How can I sort it from small to large?

Answer 1

[Walter Roberson]

symvar() sorts inconsistently if I recall correctly. It gets complicated when you start mixing numbers and underscores.

For the simple case that does not involve underscores, symvar() sorts by unicode code point

alpha = evalin(symengine, '`α`');  %unicode U+03B1
lambda = evalin(symengine, '`λ`'); %unicode U+03BB
beta = evalin(symengine, '`β`');   %unicode U+03B2
chi = evalin(symengine, '`χ`');    %unicode U+03C7
symvar([alpha,chi,lambda,beta])

ans = 

and '1' is before '2' in unicode, so X1anything occurs before X2anything

See https://www.mathworks.com/matlabcentral/fileexchange/34464-customizable-natural-order-sort

[Chen Bo-Yang]

Thanks for your answer and I use sort() to solve my problem.

[Walter Roberson]

sort() will sort by unicode code point -- but at least sort() would be consistent about what happens if you mix numbers and underscores.