prev_float

        # Float.prev_float

(from ruby core)
---
    float.prev_float  ->  float

---

Returns the next-smaller representable Float.

These examples show the internally stored values (64-bit hexadecimal)
for each Float `f` and for the corresponding `f.pev_float`:

    f = 5e-324   # 0x0000000000000001
    f.prev_float # 0x0000000000000000

    f = 0.01     # 0x3f847ae147ae147b
    f.prev_float # 0x3f847ae147ae147a

In the remaining examples here, the output is shown in the usual way
(result `to_s`):

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

    f = 0.01
    (0..3).each_with_index {|i| printf "%2d %-20a %s\n", i, f, f.to_s; f = f.prev_float }

Output:

    0 0x1.47ae147ae147bp-7 0.01
    1 0x1.47ae147ae147ap-7 0.009999999999999998
    2 0x1.47ae147ae1479p-7 0.009999999999999997
    3 0x1.47ae147ae1478p-7 0.009999999999999995

Related: Float#next_float.