cl-float-epsilon is a variable defined in `cl-lib.el'.
Its value is

  • This variable may be risky if used as a file-local variable.

The smallest positive float that adds to 1.0 to give a distinct value.
Adding a number less than this to 1.0 returns 1.0 due to roundoff.
For IEEE machines, epsilon is about 2.22e-16.
Call `cl-float-limits' to set this.