4.2.8 Variable declaration

As soon as TeXgraph encounters a name in an expression, it is examining if it’s followed by parenthesis [ex: toto(..)]:

It’s then not necessary to declare local variables, the first occurence is handled as a declaration. Though, we may need a x1 variable [for example] to be local though there is already a global variable with that name. We can tell TeXgraph to consider x1, by just adding the $ character before its name: $x1 ( adding it to the first occurence is enough ).