To convert an integer to floating point, use the function float
.
This returns number converted to floating point.
If number is already floating point, float
returns
it unchanged.
There are four functions to convert floating-point numbers to
integers; they differ in how they round. All accept an argument
number and an optional argument divisor. Both arguments
may be integers or floating-point numbers. divisor may also be
nil
. If divisor is nil
or omitted, these
functions convert number to an integer, or return it unchanged
if it already is an integer. If divisor is non-nil
, they
divide number by divisor and convert the result to an
integer. If divisor is zero (whether integer or
floating point), Emacs signals an arith-error
error.
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
This returns number, converted to an integer by rounding downward (towards negative infinity).
If divisor is specified, this uses the kind of division
operation that corresponds to mod
, rounding downward.
(floor 1.2) ⇒ 1 (floor 1.7) ⇒ 1 (floor -1.2) ⇒ -2 (floor -1.7) ⇒ -2 (floor 5.99 3) ⇒ 1
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
This returns number, converted to an integer by rounding towards the nearest integer. Rounding a value equidistant between two integers returns the even integer.
(round 1.2) ⇒ 1 (round 1.7) ⇒ 2 (round -1.2) ⇒ -1 (round -1.7) ⇒ -2