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MEP - Extend scope of ℤ to include all IEEE 754 consecutive integers

StuartBruff
23-Emerald IV

MEP - Extend scope of ℤ to include all IEEE 754 consecutive integers

Mathcad Enhancement Proposal (MEP) - Extend the scope of to include all IEEE 754 consecutive integers, where  is the set of integers.

 

Mathcad's Is-Element-Of operator xy determines whether x is an element of y, where y is one of the sets ℂ (complex numbers), ℝ (real numbers), ℚ (rational numbers), or ℤ (integers).  Is-Element-Of works both symbolically and numerically (except  in the latter's case)

  

When numerically evaluating x for membership in ℤ, x must lie between -231 and +231-1.  However, Mathcad handles numbers as 64-bit IEEE 754 floating-point numbers; thus, the full range of consecutive numerical integers in Mathcad is -253 and +253-1.

 

The maximum positive floating point real number, realmax,  is 1.7976931348623157×10308.  

 

realmax and realmax + realmax×1i ∈ ℂ both return true (1).

 

Implementing this MEP would mean Mathcad gave the correct and consistent result for all (#) Mathcad IEEE 754 64-bit numbers when evaluated against the sets ℂ, ℝ, and ℤ.

 

(I've had to implement my own isinteger function to test numbers for membership in numerical ℤ to overcome this restriction)

 

Stuart

 

(#) ∞ (infinity) is the subject of another MEP.  Numerical infinity should behave in a manner consistent with symbolic infinity. 

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