### 19.7 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

> See also: realmin.

— Built-in Function: realmin (x)
— Built-in Function: realmin (n, m)
— Built-in Function: realmin (n, m, k, ...)
— Built-in Function: realmin (..., class)

> 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

> See also: realmax.