![NaN
var nan1 = 0.0 / 0.0;
var nan2 = Number.POSITIVE_INFINITY / Number.POSITIVE_INFINITY;
var arr = [ nan1, nan2 ];
var FLOAT64_VIEW = new Float64Array( arr );
var INT32_VIEW = new Int32Array( FLOAT64_VIEW.buffer );
var isnan1 = ( FLOAT64_VIEW[0] !== FLOAT64_VIEW[0] );
// returns true
var isnan2 = ( FLOAT64_VIEW[1] !== FLOAT64_VIEW[1] );
// returns true
var bool = ( nan1 !== nan2 );
// returns true
Node v0.12 Node v4 Node v6 Node v7
Node v0.10*](https://image.slidesharecdn.com/talk-170104230446/85/Math-in-V8-is-Broken-and-How-We-Can-Fix-It-Athan-Reines-Fourier-13-320.jpg)
Math in V8 is Broken and How We Can Fix It - Athan Reines, Fourier
- 2. Math in V8 is Broken / Athan Reines @kgryte
- 6. COMPARISON
- 9. SO WHAT?
- 10. BUGS
- 11. V8 AND NODE Node EOL V8 Release 0.10.44 10-2016 3.14.5.9 05-2013 0.12.17 01-2017 3.28.71.19 11-2014 4.6.2 04-2018 4.5.103.42 08-2015 5.12.0 07-2016 4.6.85.32 11-2015 6.9.1 04-2019 5.1.281.84 07-2016 7.2.0 07-2017 5.4.500.43 11-2016
- 12. Math.sin/Math.cos var x = Math.pow( 2, 120 ); // returns 1.329227995784916e+36 var y = Math.sin( x ); // returns: -0.8783788442551665 // expected: 0.377820109360752 y = Math.cos( x ); // returns: 0.47796506772457525 // expected: -0.9258790228548378 Node v0.10
- 13. NaN var nan1 = 0.0 / 0.0; var nan2 = Number.POSITIVE_INFINITY / Number.POSITIVE_INFINITY; var arr = [ nan1, nan2 ]; var FLOAT64_VIEW = new Float64Array( arr ); var INT32_VIEW = new Int32Array( FLOAT64_VIEW.buffer ); var isnan1 = ( FLOAT64_VIEW[0] !== FLOAT64_VIEW[0] ); // returns true var isnan2 = ( FLOAT64_VIEW[1] !== FLOAT64_VIEW[1] ); // returns true var bool = ( nan1 !== nan2 ); // returns true Node v0.12 Node v4 Node v6 Node v7 Node v0.10*
- 14. Math.pow var x = Math.pow( 10, 308 ); // returns: 1.0000000000000006e+308 // expected: 1.0e+308 Node v0.10+
- 15. Algorithm function pow( x, y ) { var m = x; var n = y; var p = 1; while ( n !== 0 ) { if ( ( n & 1 ) !== 0 ) { p *= m; } m *= m; if ( ( n & 2 ) !== 0 ) { p *= m; } m *= m; n >>= 2; } return p;
- 16. Math.atanh var y = Math.atanh( 1.0e-10 ); // returns: 1.000000082640371e-10 // expected: 1.0e-10 Node v0.12 Node v4 Node v6
- 17. Math.acosh var y = Math.acosh( 1.0 + 1.0e-10 ); // returns: 0.000014142136208733941 // expected: 0.000014142136208675862 Node v0.12 Node v4 Node v6
- 18. Math.asinh var y = Math.asinh( 1.0e-50 ); // returns: 0.0 // expected: 1.0e-50 y = Math.asinh( 1.0e200 ); // returns +infinity // expected: 461.2101657793691 Node v0.12 Node v4 Node v6
- 19. Algorithm function asinh( x ) { if ( x === 0 || !isFinite( x ) ) { return x; } if ( x > 0 ) { return Math.log( x + Math.sqrt( x*x + 1 ) ); } return -Math.log( -x + Math.sqrt( x*x + 1 ) ); }
- 20. Algorithm function asinh( x ) { var sgn; var xx; var t; if ( isnan( x ) || isinfinite( x ) ) { return x; } if ( x < 0.0 ) { x = -x; sgn = true; } // Case: |x| < 2**-28 if ( x < NEAR_ZERO ) { t = x; } // Case: |x| > 2**28
- 21. Math.exp var y = Math.exp( 100.0 ); // returns: 2.6881171418161485e+43 // expected: 2.6881171418161356e+43 Node v0.12 Node v4 Node v6
- 22. Math.random uint32_t state0 = 1; uint32_t state1 = 2; uint32_t mwc1616() { state0 = 18030 * (state0 & 0xffff) + (state0 >> 16); state1 = 30903 * (state1 & 0xffff) + (state1 >> 16); return state0 << 16 + (state1 & 0xffff); } Node v0.10 Node v0.12 Node v4
- 23. Example var ALPHABET = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz012345678 function randomString( length ) { var randint; var str; var i; str = ''; for ( i = 0; i < length; i++ ) { randint = Math.floor( Math.random() * ALPHABET.length ); str += ALPHABET.substring( randint, randint+1 ); } return str; } Betable
- 24. V8 blog
- 25. JavaScript
- 26. Underspecification Cross-browser variability No single codebase Versioning Required shims Globals Testing No golden algorithms Timescale Trust
- 27. Community
- 28. Polyfills var isFinite = require( 'is-finite' ); module.exports = function asinh( x ) { if ( x === 0 || !isFinite( x ) ) { return x; } return x < 0 ? -asinh( -x ) : Math.log( x + Math.sqrt( x*x + 1 ) ); }
- 29. Libraries function asinh( x ) { return Math.log( Math.sqrt( x*x + 1 ) + x ); }
- 30. :(
- 33. Opportunities
- 34. Get Involved!
- 35. Advocate Int64/Uint64 Int128/Uint128 Typed Objects (complex) SIMD (long) Parallelism GPGPU BigFloat/BigInt
- 36. Thank you! / Athan Reines @kgryte https://github.com/stdlib-js/stdlib
- 38. APPENDIX
- 40. WHAT CAN BE DONE AT THE SPECIFICATION LEVEL?
- 41. (and bitwise ops)Int64 Typed Objects WebCL SIMD (long) Parallel Computing Operator Overloading Web Assembly
- 43. TYPED OBJECTS spec explainer typed data structures in Go
- 46. PARALLEL COMPUTING Data parallelism Task parallelism Scheduler Lock-free programming Shared Memory Web Workers
- 48. THE END