improve accuracy of Math.asinh polyfill with big values

Author: zloirock

CHANGELOG.md

@@ -5,7 +5,7 @@
   - Throw a `RangeError` on `NaN` `start` / `end` / `step`
   - Allow `null` as `optionOrStep`
   - Fixed some other edge cases
-- `Math.atanh` has become slightly more correct with small values
+- Improved accuracy of `Math.{ asinh, atanh }` polyfills with big and small values
 - Wrap `Symbol.for` in `Symbol.prototype.description` polyfill for correct handling of empty string descriptions
 - Fixed one more case (`Iterator.prototype.take`) of a V8 ~ Chromium < 126 [bug](https://issues.chromium.org/issues/336839115)
 - Forced replacement of `Iterator.{ concat, zip, zipKeyed }` in the pure version for ensuring proper wrapped `Iterator` instances as the result

packages/core-js/modules/es.math.asinh.js

@@ -5,10 +5,13 @@ var $ = require('../internals/export');
 var $asinh = Math.asinh;
 var log = Math.log;
 var sqrt = Math.sqrt;
+var LN2 = Math.LN2;
+// sqrt(2 ** 53) - prevent n * n overflow
+var SQRT_2_POW_53 = 94906265.62425156;
 
 function asinh(x) {
   var n = +x;
-  return !isFinite(n) || n === 0 ? n : n < 0 ? -asinh(-n) : log(n + sqrt(n * n + 1));
+  return !isFinite(n) || n === 0 ? n : n < 0 ? -asinh(-n) : n > SQRT_2_POW_53 ? log(n) + LN2 : log(n + sqrt(n * n + 1));
 }
 
 var FORCED = !($asinh && 1 / $asinh(0) > 0);

tests/unit-global/es.math.asinh.js

@@ -17,6 +17,10 @@ QUnit.test('Math.asinh', assert => {
   assert.closeTo(asinh(1e150), 346.0809111296668, 1e-11);
   assert.closeTo(asinh(1e7), 16.811242831518268, 1e-11);
   assert.closeTo(asinh(-1e7), -16.811242831518268, 1e-11);
+  assert.closeTo(asinh(1e200), 461.2101657793691, 1e-6, 'large value 1e200');
+  assert.closeTo(asinh(1e300), 691.4686750787736, 1e-6, 'large value 1e300');
+  assert.closeTo(asinh(Number.MAX_VALUE), 710.4758600739439, 1e-6, 'Number.MAX_VALUE');
+  assert.closeTo(asinh(-1e200), -461.2101657793691, 1e-6, 'large negative value');
 
   const checker = createConversionChecker(1234);
   assert.closeTo(asinh(checker), 7.811163549201245, 1e-11);

tests/unit-pure/es.math.asinh.js

@@ -14,6 +14,10 @@ QUnit.test('Math.asinh', assert => {
   assert.closeTo(asinh(1e150), 346.0809111296668, 1e-11);
   assert.closeTo(asinh(1e7), 16.811242831518268, 1e-11);
   assert.closeTo(asinh(-1e7), -16.811242831518268, 1e-11);
+  assert.closeTo(asinh(1e200), 461.2101657793691, 1e-6, 'large value 1e200');
+  assert.closeTo(asinh(1e300), 691.4686750787736, 1e-6, 'large value 1e300');
+  assert.closeTo(asinh(Number.MAX_VALUE), 710.4758600739439, 1e-6, 'Number.MAX_VALUE');
+  assert.closeTo(asinh(-1e200), -461.2101657793691, 1e-6, 'large negative value');
 
   const checker = createConversionChecker(1234);
   assert.closeTo(asinh(checker), 7.811163549201245, 1e-11);