Bug #16180: Random.rand(max) ignores / is broken when max ceiling value is a float

• Status: Rejected
• Assignee: -
• Target version: -
• ruby -v: ruby 2.6.3p62 (2019-04-16 revision 67580) [x86_64-darwin18]
• Backport: 2.5: UNKNOWN, 2.6: UNKNOWN

[BillyRuffian (Nigel Brookes-Thomas)]

ruby 2.6.3p62 (2019-04-16 revision 67580) [x86_64-darwin18]
ruby 2.7.0preview1 (2019-05-31 trunk c55db6aa271df4a689dc8eb0039c929bf6ed43ff) [x86_64-darwin18]

Calling rand with a float of > 1 always return 0.

Calling rand with a float 0 < value > 1 will ignore the ceiling value.

e.g.

rand(1.1)
=> 0
rand(1.1)
=> 0
rand(0.5)
=> 0.9501516156613756
rand(0.5)
=> 0.6864252478379304

[Hanmac (Hans Mackowiak)]

your cases are documented there: https://ruby-doc.org/core-2.6.4/Kernel.html#method-i-rand

When max.abs is greater than or equal to 1, rand returns a pseudo-random integer greater than or equal to 0 and less than max.to_i.abs.

Negative or floating point values for max are allowed, but may give surprising results.

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Rejected

If you want random Float values up to max, use Random#rand or Random.rand instead of Kernel#rand.