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Published equation contexts

fl(xopy)=(xopy)(1+δ),∣δ∣≤u\mathrm{fl}(x \mathbin{\text{op}} y) = (x \mathbin{\text{op}} y)(1 + \delta), \qquad |\delta| \le u

Why this formula appears here

Computers represent real numbers with a finite number of bits, following a specification — IEEE 754 — that fixes the format and the rounding behavior of arithmetic exactly enough that different compliant hardware and software give reproducible results for the same operations [ 5 ] . The standard’s core guarantee is deceptively narrow: each individual elementary operation is correctly rounded , meaning the result is the closest representable floating-point number to the true mathematical result of that one operation. For a single addition or multiplication, this means fl(xopy)=(xopy)(1+δ),∣δ∣≤u\mathrm{fl}(x \mathbin{\text{op}} y) = (x \mathbin{\text{op}} y)(1 + \delta), \qquad |\delta| \le u. where u is the unit roundoff — roughly 10^{-16} for standard double precision — and op\mathrm{op} is…

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uu

Symbol u

the unit roundoff — roughly 10^{-16} for standard double precision — and op\mathrm{op} is addition, subtraction, multiplication, or division.

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Published contexts (1)

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fl(xopy)=(xopy)(1+δ),∣δ∣≤u,\mathrm{fl}(x \mathbin{\text{op}} y) = (x \mathbin{\text{op}} y)(1 + \delta), \qquad |\delta| \le u,

Equation 1 · Mathematics

How Mathematics, Proof, and Scientific Computation Actually Work

This equation states a bound: one expression must stay on the indicated side of the other under the article’s assumptions.

Computers represent real numbers with a finite number of bits, following a specification — IEEE 754 — that fixes the format and the rounding behavior of arithmetic exactly enough that different compliant hardware and software give reproducible results for the same operations [ 5 ] . The standard’s core guarantee is deceptively narrow: each individual elementary operation is correctly rounded , meaning the result is the closest representable floating-point number to the true mathematical result of that one operation. For a single addition or multiplication, this means fl(xopy)=(xopy)(1+δ),∣δ∣≤u\mathrm{fl}(x \mathbin{\text{op}} y) = (x \mathbin{\text{op}} y)(1 + \delta), \qquad |\delta| \le u. where u is the unit roundoff — roughly 10^{-16} for standard double precision — and op\mathrm{op} is…

Meanings in this article

  • uu: the unit roundoff — roughly 10^{-16} for standard double precision — and op\mathrm{op} is addition, subtraction, multiplication, or division.
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