SWI-Prolog -- function float_fractional

Documentation
- Reference manual
  - Built-in Predicates
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      - General purpose arithmetic
        
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- Packages

Availability:Arithmetic function (see is/2)

[ISO]float_fractional_part(+Expr)

Fractional part of a floating point number. Negative if Expr is negative, rational if Expr is rational and 0 if Expr is integer. The following relation is always true: X is float_fractional_part(X) + float_integer_part(X).