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 GNU Octave Manual Version 3 by John W. Eaton, David Bateman, Søren HaubergPaperback (6"x9"), 568 pagesISBN 095461206XRRP £24.95 (\$39.95)

## 17.7 Mathematical Constants

Built-in Function: I (x)
Built-in Function: I (n, m)
Built-in Function: I (n, m, k, ...)
Built-in Function: I (..., class)
Return a matrix or N-dimensional array whose elements are all equal to the pure imaginary unit, defined as `sqrt (-1)`.

Since I (also i, J, and j) is a function, you can use the name(s) for other purposes.

Built-in Function: Inf (x)
Built-in Function: Inf (n, m)
Built-in Function: Inf (n, m, k, ...)
Built-in Function: Inf (..., class)
Return a matrix or N-dimensional array whose elements are all Infinity. The arguments are handled the same as the arguments for `eye`. The optional argument class may be either ‘"single"’ or ‘"double"’. The default is ‘"double"’.

Built-in Function: NaN (x)
Built-in Function: NaN (n, m)
Built-in Function: NaN (n, m, k, ...)
Built-in Function: NaN (..., class)
Return a matrix or N-dimensional array whose elements are all NaN (Not a Number). The value NaN is the result of an operation like 0/0, or ‘Inf - Inf’,

or any operation with a NaN.

Note that NaN always compares not equal to NaN. This behavior is specified by the IEEE standard for floating point arithmetic. To find NaN values, you must use the `isnan` function.

The arguments are handled the same as the arguments for `eye`. The optional argument class may be either ‘"single"’ or ‘"double"’. The default is ‘"double"’.

Built-in Function: pi (x)
Built-in Function: pi (n, m)
Built-in Function: pi (n, m, k, ...)
Built-in Function: pi (..., class)
Return a matrix or N-dimensional array whose elements are all equal to the ratio of the circumference of a circle to its diameter. Internally, `pi` is computed as ‘4.0 * atan (1.0)’.

Built-in Function: e (x)
Built-in Function: e (n, m)
Built-in Function: e (n, m, k, ...)
Built-in Function: e (..., class)
Return a matrix or N-dimensional array whose elements are all equal to the base of natural logarithms. The constant e

satisfies the equation `log` (e) = 1.

Built-in Function: eps (x)
Built-in Function: eps (n, m)
Built-in Function: eps (n, m, k, ...)
Built-in Function: eps (..., class)
Return a matrix or N-dimensional array whose elements are all eps, the machine precision. More precisely, `eps` is the largest relative spacing between any two adjacent numbers in the machine's floating point system. This number is obviously system-dependent. On machines that support 64-bit IEEE floating point arithmetic, `eps` is approximately 2.2204e-16.

Built-in Function: realmax (x)
Built-in Function: realmax (n, m)
Built-in Function: realmax (n, m, k, ...)
Built-in Function: realmax (..., class)
Return a matrix or N-dimensional array whose elements are all equal to the largest floating point number that is representable. The actual value is system-dependent. On machines that support 64-bit IEEE floating point arithmetic, `realmax` is approximately 1.7977e+308

Return a matrix or N-dimensional array whose elements are all equal to the smallest normalized floating point number that is representable. The actual value is system-dependent. On machines that support 64-bit IEEE floating point arithmetic, `realmin` is approximately 2.2251e-308