The name undefined is a reserved word in Maple that can be produced and propagated in various ways, usually as the result of attempting to carry out an operation which cannot result in a number for the given operands.

undefined's typically result from operations in which one or more operands are undefined, or, in the absence of a trap (see events), from invalid operations or mathematical operations for which no single numeric value can represent the result.

In floating-point computations, the value Float(undefined) corresponds to the IEEE arithmetic representation for Not-a-Number (NaN).

undefined's from different computation environments (exact, software floats, etc.) are converted to the relevant computation environment when they occur in a mixed computation.

The Boolean evaluation of evalb(undefined <> undefined) always returns false.

To test for exactly the value undefined, as opposed to any of its variants, such as Float(undefined) or undefined+I*undefined, use the test type(expr, NumericClass(undefined)).

$0\mathrm{\infty }$

$\mathrm{undefined}$

$\mathrm{\infty }-\mathrm{\infty }$

$\mathrm{undefined}$

$\mathrm{frem}\left(\mathrm{\infty }\&comma;2\right)$

$Float\left(\mathrm{undefined}\right)$

$\mathrm{CopySign}\left(1\&comma;2\mathrm{I}\right)$

$\mathrm{undefined}$

$\mathrm{NextAfter}\left(1\&comma;2\mathrm{I}\right)$

$\mathrm{undefined}$

$\mathrm{evalb}\left(\mathrm{undefined}\ne \mathrm{undefined}\right)$

$\mathrm{false}$