This error appears when there are unmatched brackets or other delimiters or operators within an expression. For example, the bracket delimiters (, ), [, ], {, }, <, and > work in pairs, and an error occurs if a bracket is used and cannot be matched with its pair.

Tip: If an expression is executed accidentally, it can lead to error messages (if it is not valid Maple syntax). If this happens, toggling the expression to nonexecutable math removes the error message and changes the math to nonexecutable. To change an expression to nonexecutable math use the shortcut key Shift + F5.  For more information, see Executable and Nonexecutable Math.

Example 1

This first example is missing the right parenthesis:

To fix the problem, the matching parenthesis needs to be added:

Example 2

Often, large expressions with multiple sets of delimiters can be confusing, and it is easy to leave one out:

To fix the problem, make sure that each set of delimiters is complete:

To help identify matched sets of delimiters in your work, see Bracket Matching in the Options Dialog - Interface Tab help page.

Example 3

Mixing delimiter types can also cause this error to be returned. In this example, a parenthesis and a brace are used together:

Ensure that matching sets of delimiters are used.