floatp

floatp Function

Syntax:

floatp object

generalized-boolean

Arguments and Values:

object—an object.

generalized-boolean—a generalized boolean.

Description:

Returns true if object is of type float; otherwise, returns false.

Examples:

(floatp 1.2d2) *! true* 
(floatp 1.212) *! true* 
(floatp 1.2s2) *! true* 
(floatp (expt 2 130)) *! false* 

Notes:

(floatp object) ⌘ (typep object ’float)

most-positive-short-float, least-positive-short-float, ... ^{most-positive-short-float, least-positive-short float, least-positive-normalized-short-float, most} positive-double-float, least-positive-double-float, ^{least-positive-normalized-double-float, most positive-long-float, least-positive-long-float, least positive-normalized-long-float, most-positive single-float, least-positive-single-float, least positive-normalized-single-float, most-negative short-float, least-negative-short-float, least negative-normalized-short-float, most-negative single-float, least-negative-single-float, least negative-normalized-single-float, most-negative double-float, least-negative-double-float, least negative-normalized-double-float, most-negative long-float, least-negative-long-float, least-negative} normalized-long-float Constant Variable

Constant Value:

implementation-dependent.

Description:

These constant variables provide a way for programs to examine the implementation-defined limits for the various float formats.

Of these variables, each which has “-normalized” in its name must have a value which is a normalized float, and each which does not have “-normalized” in its name may have a value which is either a normalized float or a denormalized float, as appropriate.

Of these variables, each which has “short-float” in its name must have a value which is a short float, each which has “single-float” in its name must have a value which is a single float, each which has “double-float” in its name must have a value which is a double float, and each which has “long-float” in its name must have a value which is a long float.

• most-positive-short-float, most-positive-single-float,

most-positive-double-float, most-positive-long-float

Each of these constant variables has as its value the positive float of the largest magnitude

(closest in value to, but not equal to, positive infinity) for the float format implied by its name.

• least-positive-short-float, least-positive-normalized-short-float,

least-positive-single-float, least-positive-normalized-single-float,

least-positive-double-float, least-positive-normalized-double-float,

least-positive-long-float, least-positive-normalized-long-float

Each of these constant variables has as its value the smallest positive (nonzero) float for the float format implied by its name.

• least-negative-short-float, least-negative-normalized-short-float,

least-negative-single-float, least-negative-normalized-single-float,

least-negative-double-float, least-negative-normalized-double-float,

least-negative-long-float, least-negative-normalized-long-float

Each of these constant variables has as its value the negative (nonzero) float of the smallest magnitude for the float format implied by its name. (If an implementation supports minus zero as a di↵erent object from positive zero, this value must not be minus zero.)

• most-negative-short-float, most-negative-single-float,

most-negative-double-float, most-negative-long-float

Each of these constant variables has as its value the negative float of the largest magnitude (closest in value to, but not equal to, negative infinity) for the float format implied by its name.

Notes:

Expanded Reference: floatp

Testing if an object is a float

floatp returns true if the object is a floating-point number.

(floatp 3.14)
=> T
(floatp 1.0)
=> T
(floatp 1.2d2)
=> T
(floatp 1.2s2)
=> T

Non-float numbers

Integers, ratios, and complex numbers are not floats.

(floatp 42)
=> NIL
(floatp 1/3)
=> NIL
(floatp #c(1.0 2.0))
=> NIL
(floatp (expt 2 130))
=> NIL

Non-numeric objects

floatp returns false for all non-numeric types.

(floatp nil)
=> NIL
(floatp "3.14")
=> NIL
(floatp 'pi)
=> NIL

Different float formats

Common Lisp supports short, single, double, and long floats. floatp returns true for all of them.

(floatp 1.0s0)
=> T
(floatp 1.0f0)
=> T
(floatp 1.0d0)
=> T
(floatp 1.0l0)
=> T

Equivalence to typep

floatp is equivalent to (typep object 'float).

(eql (floatp 3.14) (typep 3.14 'float))
=> T
(eql (floatp 42) (typep 42 'float))
=> T