Class: Float

Return values corresponding to the value of float:

finite

nil

-Infinity

-1

+Infinity

1

For example:

(0.0).infinite?        #=> nil
(-1.0/0.0).infinite?   #=> -1
(+1.0/0.0).infinite?   #=> 1

Returns true if float is an invalid IEEE floating point number.

a = -1.0      #=> -1.0
a.nan?        #=> false
a = 0.0/0.0   #=> NaN
a.nan?        #=> true

Returns true if float is less than 0.

Returns true if float is greater than 0.

Returns true if float is 0.0.

Returns a new float which is the product of float and other.

Raises float to the power of other.

2.0**3      #=> 8.0

Returns a new float which is the sum of float and other.

Returns a new float which is the difference of float and other.

Returns float, negated.

Returns a new float which is the result of dividing float by other.

Returns true if float is less than real.

The result of NaN < NaN is undefined, so the implementation-dependent value is returned.

Returns true if float is less than or equal to real.

The result of NaN <= NaN is undefined, so the implementation-dependent value is returned.

Returns -1, 0, +1 or nil depending on whether float is less than, equal to, or greater than real. This is the basis for the tests in ::Comparable.

The result of NaN <=> NaN is undefined, so the implementation-dependent value is returned.

nil is returned if the two values are incomparable.

Returns true only if obj has the same value as float. Contrast this with #eql?, which requires obj to be a Float.

The result of NaN == NaN is undefined, so the implementation-dependent value is returned.

1.0 == 1   #=> true

Alias for #==.

Returns true if float is greater than real.

The result of NaN > NaN is undefined, so the implementation-dependent value is returned.

Returns true if float is greater than or equal to real.

The result of NaN >= NaN is undefined, so the implementation-dependent value is returned.

Returns the absolute value of float.

(-34.56).abs   #=> 34.56
-34.56.abs     #=> 34.56

Alias for #arg.

Returns 0 if the value is positive, pi otherwise.

Returns the smallest number greater than or equal to float in decimal digits (default 0 digits).

Precision may be negative. Returns a floating point number when ndigits is positive, self for zero, and ceil up for negative.

1.2.ceil      #=> 2
2.0.ceil      #=> 2
(-1.2).ceil   #=> -1
(-2.0).ceil   #=> -2
1.234567.ceil(2)  #=> 1.24
1.234567.ceil(3)  #=> 1.235
1.234567.ceil(4)  #=> 1.2346
1.234567.ceil(5)  #=> 1.23457

34567.89.ceil(-5) #=> 100000
34567.89.ceil(-4) #=> 40000
34567.89.ceil(-3) #=> 35000
34567.89.ceil(-2) #=> 34600
34567.89.ceil(-1) #=> 34570
34567.89.ceil(0)  #=> 34568
34567.89.ceil(1)  #=> 34567.9
34567.89.ceil(2)  #=> 34567.89
34567.89.ceil(3)  #=> 34567.89

Returns an array with both a numeric and a float represented as Float objects.

This is achieved by converting a numeric to a Float.

1.2.coerce(3)       #=> [3.0, 1.2]
2.5.coerce(1.1)     #=> [1.1, 2.5]

Returns the denominator (always positive). The result is machine dependent.

See numerator.

See Numeric#divmod.

42.0.divmod 6 #=> [7, 0.0]
42.0.divmod 5 #=> [8, 2.0]

Returns true only if obj is a Float with the same value as float. Contrast this with #==, which performs type conversions.

The result of NaN.eql?(NaN) is undefined, so the implementation-dependent value is returned.

1.0.eql?(1)   #=> false

Alias for #quo.

Returns the largest number less than or equal to float in decimal digits (default 0 digits).

Precision may be negative. Returns a floating point number when ndigits is positive, self for zero, and floor down for negative.

1.2.floor      #=> 1
2.0.floor      #=> 2
(-1.2).floor   #=> -2
(-2.0).floor   #=> -2

1.234567.floor(2)  #=> 1.23
1.234567.floor(3)  #=> 1.234
1.234567.floor(4)  #=> 1.2345
1.234567.floor(5)  #=> 1.23456

34567.89.floor(-5) #=> 0
34567.89.floor(-4) #=> 30000
34567.89.floor(-3) #=> 34000
34567.89.floor(-2) #=> 34500
34567.89.floor(-1) #=> 34560
34567.89.floor(0)  #=> 34567
34567.89.floor(1)  #=> 34567.8
34567.89.floor(2)  #=> 34567.89
34567.89.floor(3)  #=> 34567.89

Returns a hash code for this float.

See also Object#hash.

Alias for #to_s.

Alias for #abs.

Alias for #%.

Returns the next representable floating-point number.

Float::MAX.next_float and Float::INFINITY.next_float is INFINITY.

Float::NAN.next_float is NAN.

For example:

p 0.01.next_float  #=> 0.010000000000000002
p 1.0.next_float   #=> 1.0000000000000002
p 100.0.next_float #=> 100.00000000000001

p 0.01.next_float - 0.01   #=> 1.734723475976807e-18
p 1.0.next_float - 1.0     #=> 2.220446049250313e-16
p 100.0.next_float - 100.0 #=> 1.4210854715202004e-14

f = 0.01; 20.times { printf "%-20a %s\n", f, f.to_s; f = f.next_float }
#=> 0x1.47ae147ae147bp-7 0.01
#   0x1.47ae147ae147cp-7 0.010000000000000002
#   0x1.47ae147ae147dp-7 0.010000000000000004
#   0x1.47ae147ae147ep-7 0.010000000000000005
#   0x1.47ae147ae147fp-7 0.010000000000000007
#   0x1.47ae147ae148p-7  0.010000000000000009
#   0x1.47ae147ae1481p-7 0.01000000000000001
#   0x1.47ae147ae1482p-7 0.010000000000000012
#   0x1.47ae147ae1483p-7 0.010000000000000014
#   0x1.47ae147ae1484p-7 0.010000000000000016
#   0x1.47ae147ae1485p-7 0.010000000000000018
#   0x1.47ae147ae1486p-7 0.01000000000000002
#   0x1.47ae147ae1487p-7 0.010000000000000021
#   0x1.47ae147ae1488p-7 0.010000000000000023
#   0x1.47ae147ae1489p-7 0.010000000000000024
#   0x1.47ae147ae148ap-7 0.010000000000000026
#   0x1.47ae147ae148bp-7 0.010000000000000028
#   0x1.47ae147ae148cp-7 0.01000000000000003
#   0x1.47ae147ae148dp-7 0.010000000000000031
#   0x1.47ae147ae148ep-7 0.010000000000000033

f = 0.0
100.times { f += 0.1 }
p f                            #=> 9.99999999999998       # should be 10.0 in the ideal world.
p 10-f                         #=> 1.9539925233402755e-14 # the floating-point error.
p(10.0.next_float-10)          #=> 1.7763568394002505e-15 # 1 ulp (units in the last place).
p((10-f)/(10.0.next_float-10)) #=> 11.0                   # the error is 11 ulp.
p((10-f)/(10*Float::EPSILON))  #=> 8.8                    # approximation of the above.
p "%a" % f                     #=> "0x1.3fffffffffff5p+3" # the last hex digit is 5.  16 - 5 = 11 ulp.

Returns the numerator. The result is machine dependent.

n = 0.3.numerator    #=> 5404319552844595
d = 0.3.denominator  #=> 18014398509481984
n.fdiv(d)            #=> 0.3

Alias for #arg.

Returns the previous representable floating-point number.

(-Float::MAX).prev_float and (-Float::INFINITY).prev_float is -Float::INFINITY.

Float::NAN.prev_float is NAN.

For example:

p 0.01.prev_float  #=> 0.009999999999999998
p 1.0.prev_float   #=> 0.9999999999999999
p 100.0.prev_float #=> 99.99999999999999

p 0.01 - 0.01.prev_float   #=> 1.734723475976807e-18
p 1.0 - 1.0.prev_float     #=> 1.1102230246251565e-16
p 100.0 - 100.0.prev_float #=> 1.4210854715202004e-14

f = 0.01; 20.times { printf "%-20a %s\n", f, f.to_s; f = f.prev_float }
#=> 0x1.47ae147ae147bp-7 0.01
#   0x1.47ae147ae147ap-7 0.009999999999999998
#   0x1.47ae147ae1479p-7 0.009999999999999997
#   0x1.47ae147ae1478p-7 0.009999999999999995
#   0x1.47ae147ae1477p-7 0.009999999999999993
#   0x1.47ae147ae1476p-7 0.009999999999999992
#   0x1.47ae147ae1475p-7 0.00999999999999999
#   0x1.47ae147ae1474p-7 0.009999999999999988
#   0x1.47ae147ae1473p-7 0.009999999999999986
#   0x1.47ae147ae1472p-7 0.009999999999999985
#   0x1.47ae147ae1471p-7 0.009999999999999983
#   0x1.47ae147ae147p-7  0.009999999999999981
#   0x1.47ae147ae146fp-7 0.00999999999999998
#   0x1.47ae147ae146ep-7 0.009999999999999978
#   0x1.47ae147ae146dp-7 0.009999999999999976
#   0x1.47ae147ae146cp-7 0.009999999999999974
#   0x1.47ae147ae146bp-7 0.009999999999999972
#   0x1.47ae147ae146ap-7 0.00999999999999997
#   0x1.47ae147ae1469p-7 0.009999999999999969
#   0x1.47ae147ae1468p-7 0.009999999999999967

Returns float / numeric, same as #/.

Returns a simpler approximation of the value (flt-|eps| <= result <= flt+|eps|). if the optional eps is not given, it will be chosen automatically.

0.3.rationalize          #=> (3/10)
1.333.rationalize        #=> (1333/1000)
1.333.rationalize(0.01)  #=> (4/3)

See to_r.

Rounds float to a given precision in decimal digits (default 0 digits).

Precision may be negative. Returns a floating point number when ndigits is more than zero.

1.4.round      #=> 1
1.5.round      #=> 2
1.6.round      #=> 2
(-1.5).round   #=> -2

1.234567.round(2)  #=> 1.23
1.234567.round(3)  #=> 1.235
1.234567.round(4)  #=> 1.2346
1.234567.round(5)  #=> 1.23457

34567.89.round(-5) #=> 0
34567.89.round(-4) #=> 30000
34567.89.round(-3) #=> 35000
34567.89.round(-2) #=> 34600
34567.89.round(-1) #=> 34570
34567.89.round(0)  #=> 34568
34567.89.round(1)  #=> 34567.9
34567.89.round(2)  #=> 34567.89
34567.89.round(3)  #=> 34567.89

If half: optional keyword is given, just-half number will be rounded according to that value. Supported values for this keyword are follows.

• :up or nil: the result will be rounded away from zero

• :even: the result will be rounded to nearest even number

• :down: the result will be rounded close to zero

Since float is already a float, returns self.

Returns the float truncated to an ::Integer.

Synonyms are #to_i and #to_int

Alias for #to_i.

Returns the value as a rational.

NOTE: 0.3.to_r isn't the same as '0.3'.to_r. The latter is equivalent to '3/10'.to_r, but the former isn't so.

2.0.to_r    #=> (2/1)
2.5.to_r    #=> (5/2)
-0.75.to_r  #=> (-3/4)
0.0.to_r    #=> (0/1)

See rationalize.

Returns a string containing a representation of self. As well as a fixed or exponential form of the float, the call may return NaN, Infinity, and -Infinity.

Truncates float to a given precision in decimal digits (default 0 digits).

Precision may be negative. Returns a floating point number when ndigits is more than zero.