### 9.4.4 List of variables of an algebraic expressions

The algvar command finds the symbolic variable names in an expression and orders them.

- algvar takes expr, an expression.
- algvar(expr) returns the list of the symbolic variable names used in expr, ordered by the algebraic extensions required to build expr.

#### Examples

algvar(y+x*sqrt(z))

| ⎡ ⎣ | ⎡ ⎣ | y,x | ⎤ ⎦ | , | ⎡ ⎣ | z | ⎤ ⎦ | ⎤ ⎦

algvar(y*sqrt(x)*sqrt(z))

⎡
⎢
⎢
⎣

y
z
x

⎤
⎥
⎥
⎦

algvar(y*sqrt(x*z))

| ⎡ ⎣ | ⎡ ⎣ | y | ⎤ ⎦ | , | ⎡ ⎣ | x,z | ⎤ ⎦ | ⎤ ⎦

algvar(y+x*sqrt(z)+y*sin(x))

| ⎡ ⎣ | ⎡ ⎣ | y,x,sin x | ⎤ ⎦ | , | ⎡ ⎣ | z | ⎤ ⎦ | ⎤ ⎦