Numeric Conversions
===================
To convert an integer to floating point, use the function `float'.
- Function: float number
This returns NUMBER converted to floating point. If NUMBER is
already a floating point number, `float' returns it unchanged.
There are four functions to convert floating point numbers to
integers; they differ in how they round. These functions accept
integer arguments also, and return such arguments unchanged.
- Function: truncate number
This returns NUMBER, converted to an integer by rounding towards
zero.
(truncate 1.2)
=> 1
(truncate 1.7)
=> 1
(truncate -1.2)
=> -1
(truncate -1.7)
=> -1
- Function: floor number &optional divisor
This returns NUMBER, converted to an integer by rounding downward
(towards negative infinity).
If DIVISOR is specified, `floor' divides NUMBER by DIVISOR and
then converts to an integer; this uses the kind of division
operation that corresponds to `mod', rounding downward. An
`arith-error' results if DIVISOR is 0.
(floor 1.2)
=> 1
(floor 1.7)
=> 1
(floor -1.2)
=> -2
(floor -1.7)
=> -2
(floor 5.99 3)
=> 1
- Function: ceiling number
This returns NUMBER, converted to an integer by rounding upward
(towards positive infinity).
(ceiling 1.2)
=> 2
(ceiling 1.7)
=> 2
(ceiling -1.2)
=> -1
(ceiling -1.7)
=> -1
- Function: round number
This returns NUMBER, converted to an integer by rounding towards
the nearest integer. Rounding a value equidistant between two
integers may choose the integer closer to zero, or it may prefer
an even integer, depending on your machine.
(round 1.2)
=> 1
(round 1.7)
=> 2
(round -1.2)
=> -1
(round -1.7)
=> -2