The following names have special values in Matlab.

Value | Comment |
---|---|

ans | the last computed answer |

eps | the smallest number such that 1 + eps ~= 1 |

realmin | the smallest representable positive real number |

realmax | the largest representable positive real number |

pi | 3.141592653589... |

i, j | sqrt(-1) |

Inf | IEEE representation of positive infinity (1/0, factorial(200) |

NaN | IEEE representation of not-a-number (inf - inf, 0/0) |

To get the value e = 2.7182818284..., use `exp(1)`.

The following boolean valued queries are available to test for various values. They map onto matrices.

- isfininte
- isinf
- isnan

The function `isfinite` returns true if the number is
any floating point value which is not `NaN` or `Inf`.

The function `isinf` tests if
either the real or imaginary part of a number is infinity. For example,
the following are all recognized as infinity:
`Inf`, `-Inf + NaN*i`, and `-Inf*i`.

The function `isnan` tests if
either the real or imaginary part of a number is not-a-number.
A requirement of IEEE numerics is
that *NaN* does not compare to itself, as can be seen in the
following example:

>> NaN == NaN ans = 0 >> isnan( NaN ) ans = 1