The evaln function is used to "evaluate to a name" or, more generally, to form an assignable object. The name (assignable object) will not itself be evaluated.

A typical example of its use would be divide(a,b,evaln(t[i])) where i is the index of a for loop.

If the expression is a simple name (i.e. a symbol) then the same effect can be achieved by using single quotes on the name.

evaln can be used on names, subscripts, function calls, and concatenations.

There is also a procedure parameter modifier, evaln, which declares that an argument to a procedure invocation must evaluate to a name.

The evaln command is thread-safe as of Maple 15.

For more information on thread safety, see index/threadsafe.

Error, illegal use of an object as a name