Documentation

# `undefined`

Undefined value

MuPAD® notebooks will be removed in a future release. Use MATLAB® live scripts instead.

MATLAB live scripts support most MuPAD functionality, though there are some differences. For more information, see Convert MuPAD Notebooks to MATLAB Live Scripts.

## Description

`undefined` indicates results of mathematically undefined operations.

MuPAD® uses the special value `undefined` to indicate the results of operations that are not defined in mathematics.

You can use the `undefined` value as an input. Arithmetical operations involving `undefined` also return `undefined`. Multiplying infinities by 0 returns `undefined`.

For floating-point values, MuPAD uses the special value `RD_NAN` instead of `undefined`. If you use typeset mode, MuPAD displays `RD_NAN` as `NaN` in output regions. Multiplying infinities `RD_INF` and `RD_NINF` by 0 returns `RD_NAN`.

## Examples

### Example 1

Perform the following operations with infinities. MuPAD returns the `undefined` value for these operations:

`0*infinity, infinity - infinity, infinity/infinity`

### Example 2

Compute the limit of the sine function at infinity. Since this limit does not exist (is not mathematically defined), MuPAD returns `undefined`:

`limit(sin(x), x = infinity)`

### Example 3

Multiply infinities by 0:

`infinity*0, -infinity*0`

`RD_INF*0, RD_NINF*0`