Data.AEq

Methods

• (===) :: a -> a -> Boolinfix 4

  An exact equality comparison.

  For real IEEE types, two values are equivalent in the following cases:

  • both values are +0;

  • both values are -0;

  • both values are nonzero and equal to each other (according to ==);

  • both values are NaN with the same payload and sign.

  For complex IEEE types, two values are equivalent if their real and imaginary parts are equivalent.

• (~==) :: a -> a -> Boolinfix 4

  An approximate equality comparison operator.

  For real IEEE types, two values are approximately equal in the following cases:

  • at least half of their significand bits agree;

  • both values are less than epsilon;

  • both values are NaN.

  For complex IEEE types, two values are approximately equal in the followiing cases:

  • their magnitudes are approximately equal and the angle between them is less than 32*epsilon;

  • both magnitudes are less than epsilon;

  • both have a NaN real or imaginary part.

  Admitedly, the 32 is a bit of a hack. Future versions of the library may switch to a more principled test of the angle.