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| 12 Numbers 12.1 Number Concepts 12.1.4 Floating-point Computations 12.1.4.1 Rule of Float and Rational Contagion ### 12.1.4.1.1 Examples of Rule of Float and Rational Contagion
     ;;;; Combining rationals with floats.
     ;;; This example assumes an implementation in which
     ;;; (float-radix 0.5) is 2 (as in IEEE) or 16 (as in IBM/360),
     ;;; or else some other implementation in which 1/2 has an exact
     ;;;  representation in floating point.
     (+ 1/2 0.5)  1.0
     (- 1/2 0.5d0)  0.0d0
     (+ 0.5 -0.5 1/2)  0.5

     ;;;; Comparing rationals with floats.
     ;;; This example assumes an implementation in which the default float
     ;;; format is IEEE single-float, IEEE double-float, or some other format
     ;;; in which 5/7 is rounded upwards by FLOAT.
     (< 5/7 (float 5/7))  true
     (< 5/7 (rational (float 5/7)))  true
     (< (float 5/7) (float 5/7))  false

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