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'use strict'; // based on Shewchuk's algorithm for exactly floating point addition
// adapted from https://github.com/tc39/proposal-math-sum/blob/3513d58323a1ae25560e8700aa5294500c6c9287/polyfill/polyfill.mjs
var $ = require('../internals/export'); var uncurryThis = require('../internals/function-uncurry-this'); var iterate = require('../internals/iterate');
var $RangeError = RangeError; var $TypeError = TypeError; var $Infinity = Infinity; var $NaN = NaN; var abs = Math.abs; var pow = Math.pow; var push = uncurryThis([].push);
var POW_2_1023 = pow(2, 1023); var MAX_SAFE_INTEGER = pow(2, 53) - 1; // 2 ** 53 - 1 === 9007199254740992
var MAX_DOUBLE = Number.MAX_VALUE; // 2 ** 1024 - 2 ** (1023 - 52) === 1.79769313486231570815e+308
var MAX_ULP = pow(2, 971); // 2 ** (1023 - 52) === 1.99584030953471981166e+292
var NOT_A_NUMBER = {}; var MINUS_INFINITY = {}; var PLUS_INFINITY = {}; var MINUS_ZERO = {}; var FINITE = {};
// prerequisite: abs(x) >= abs(y)
var twosum = function (x, y) { var hi = x + y; var lo = y - (hi - x); return { hi: hi, lo: lo }; };
// `Math.sumPrecise` method
// https://github.com/tc39/proposal-math-sum
$({ target: 'Math', stat: true }, { // eslint-disable-next-line max-statements -- ok
sumPrecise: function sumPrecise(items) { var numbers = []; var count = 0; var state = MINUS_ZERO;
iterate(items, function (n) { if (++count >= MAX_SAFE_INTEGER) throw new $RangeError('Maximum allowed index exceeded'); if (typeof n != 'number') throw new $TypeError('Value is not a number'); if (state !== NOT_A_NUMBER) { // eslint-disable-next-line no-self-compare -- NaN check
if (n !== n) state = NOT_A_NUMBER; else if (n === $Infinity) state = state === MINUS_INFINITY ? NOT_A_NUMBER : PLUS_INFINITY; else if (n === -$Infinity) state = state === PLUS_INFINITY ? NOT_A_NUMBER : MINUS_INFINITY; else if ((n !== 0 || (1 / n) === $Infinity) && (state === MINUS_ZERO || state === FINITE)) { state = FINITE; push(numbers, n); } } });
switch (state) { case NOT_A_NUMBER: return $NaN; case MINUS_INFINITY: return -$Infinity; case PLUS_INFINITY: return $Infinity; case MINUS_ZERO: return -0; }
var partials = []; var overflow = 0; // conceptually 2 ** 1024 times this value; the final partial is biased by this amount
var x, y, sum, hi, lo, tmp;
for (var i = 0; i < numbers.length; i++) { x = numbers[i]; var actuallyUsedPartials = 0; for (var j = 0; j < partials.length; j++) { y = partials[j]; if (abs(x) < abs(y)) { tmp = x; x = y; y = tmp; } sum = twosum(x, y); hi = sum.hi; lo = sum.lo; if (abs(hi) === $Infinity) { var sign = hi === $Infinity ? 1 : -1; overflow += sign;
x = (x - (sign * POW_2_1023)) - (sign * POW_2_1023); if (abs(x) < abs(y)) { tmp = x; x = y; y = tmp; } sum = twosum(x, y); hi = sum.hi; lo = sum.lo; } if (lo !== 0) partials[actuallyUsedPartials++] = lo; x = hi; } partials.length = actuallyUsedPartials; if (x !== 0) push(partials, x); }
// compute the exact sum of partials, stopping once we lose precision
var n = partials.length - 1; hi = 0; lo = 0;
if (overflow !== 0) { var next = n >= 0 ? partials[n] : 0; n--; if (abs(overflow) > 1 || (overflow > 0 && next > 0) || (overflow < 0 && next < 0)) { return overflow > 0 ? $Infinity : -$Infinity; } // here we actually have to do the arithmetic
// drop a factor of 2 so we can do it without overflow
// assert(abs(overflow) === 1)
sum = twosum(overflow * POW_2_1023, next / 2); hi = sum.hi; lo = sum.lo; lo *= 2; if (abs(2 * hi) === $Infinity) { // rounding to the maximum value
if (hi > 0) { return (hi === POW_2_1023 && lo === -(MAX_ULP / 2) && n >= 0 && partials[n] < 0) ? MAX_DOUBLE : $Infinity; } return (hi === -POW_2_1023 && lo === (MAX_ULP / 2) && n >= 0 && partials[n] > 0) ? -MAX_DOUBLE : -$Infinity; }
if (lo !== 0) { partials[++n] = lo; lo = 0; }
hi *= 2; }
while (n >= 0) { sum = twosum(hi, partials[n--]); hi = sum.hi; lo = sum.lo; if (lo !== 0) break; }
if (n >= 0 && ((lo < 0 && partials[n] < 0) || (lo > 0 && partials[n] > 0))) { y = lo * 2; x = hi + y; if (y === x - hi) hi = x; }
return hi; } });
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