v147 · JavaScript · demo

Sum REPL

Type comma-separated numbers and instantly see the naive sum, Math.sumPrecise result, and the exact difference between them.

Naive sum

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Math.sumPrecise

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Difference

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const nums = [0.1, 0.1, 0.1, 0.1, 0.1, 0.1, 0.1, 0.1, 0.1, 0.1];

// Naive: accumulated rounding error
let naive = 0;
for (const n of nums) naive += n;
console.log(naive); // 0.9999999999999999

// Precise: compensated algorithm (Chrome 147+)
const precise = Math.sumPrecise(nums);
console.log(precise); // 1

// Difference
console.log(Math.abs(naive - precise)); // 1.1102230246251565e-16

see also

implementation reference

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