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Floating-point-operations

Float-minus

Unary minus - on floats [JLS14:4.2.4] [JLS14:15.15.4].

Signature
(float-minus operand) → result
Arguments: operand — Guard (float-valuep operand).
Returns: result — Type (float-valuep result).

Definitions and Theorems

Function: float-minus

(defun float-minus (operand)
  (declare (xargs :guard (float-valuep operand)))
  (b* ((x (float-value->float operand)))
    (float-value (float-minus-abs x))))

Theorem: float-valuep-of-float-minus

(defthm float-valuep-of-float-minus
  (b* ((result (float-minus operand)))
    (float-valuep result))
  :rule-classes :rewrite)

Theorem: float-minus-of-float-value-fix-operand

(defthm float-minus-of-float-value-fix-operand
  (equal (float-minus (float-value-fix operand))
         (float-minus operand)))

Theorem: float-minus-float-value-equiv-congruence-on-operand

(defthm float-minus-float-value-equiv-congruence-on-operand
  (implies (float-value-equiv operand operand-equiv)
           (equal (float-minus operand)
                  (float-minus operand-equiv)))
  :rule-classes :congruence)