| 1437 | } |
| 1438 | |
| 1439 | static XlaOp I0eImpl64(XlaOp x) { |
| 1440 | static const std::array<double, 30> kI0eCoeffsA{ |
| 1441 | -4.41534164647933937950E-18, 3.33079451882223809783E-17, |
| 1442 | -2.43127984654795469359E-16, 1.71539128555513303061E-15, |
| 1443 | -1.16853328779934516808E-14, 7.67618549860493561688E-14, |
| 1444 | -4.85644678311192946090E-13, 2.95505266312963983461E-12, |
| 1445 | -1.72682629144155570723E-11, 9.67580903537323691224E-11, |
| 1446 | -5.18979560163526290666E-10, 2.65982372468238665035E-9, |
| 1447 | -1.30002500998624804212E-8, 6.04699502254191894932E-8, |
| 1448 | -2.67079385394061173391E-7, 1.11738753912010371815E-6, |
| 1449 | -4.41673835845875056359E-6, 1.64484480707288970893E-5, |
| 1450 | -5.75419501008210370398E-5, 1.88502885095841655729E-4, |
| 1451 | -5.76375574538582365885E-4, 1.63947561694133579842E-3, |
| 1452 | -4.32430999505057594430E-3, 1.05464603945949983183E-2, |
| 1453 | -2.37374148058994688156E-2, 4.93052842396707084878E-2, |
| 1454 | -9.49010970480476444210E-2, 1.71620901522208775349E-1, |
| 1455 | -3.04682672343198398683E-1, 6.76795274409476084995E-1}; |
| 1456 | |
| 1457 | static const std::array<double, 25> kI0eCoeffsB{ |
| 1458 | -7.23318048787475395456E-18, -4.83050448594418207126E-18, |
| 1459 | 4.46562142029675999901E-17, 3.46122286769746109310E-17, |
| 1460 | -2.82762398051658348494E-16, -3.42548561967721913462E-16, |
| 1461 | 1.77256013305652638360E-15, 3.81168066935262242075E-15, |
| 1462 | -9.55484669882830764870E-15, -4.15056934728722208663E-14, |
| 1463 | 1.54008621752140982691E-14, 3.85277838274214270114E-13, |
| 1464 | 7.18012445138366623367E-13, -1.79417853150680611778E-12, |
| 1465 | -1.32158118404477131188E-11, -3.14991652796324136454E-11, |
| 1466 | 1.18891471078464383424E-11, 4.94060238822496958910E-10, |
| 1467 | 3.39623202570838634515E-9, 2.26666899049817806459E-8, |
| 1468 | 2.04891858946906374183E-7, 2.89137052083475648297E-6, |
| 1469 | 6.88975834691682398426E-5, 3.36911647825569408990E-3, |
| 1470 | 8.04490411014108831608E-1}; |
| 1471 | |
| 1472 | x = Abs(x); |
| 1473 | auto half = xla::ScalarLike(x, 0.5); |
| 1474 | auto two = xla::ScalarLike(x, 2.0); |
| 1475 | auto thirty_two = xla::ScalarLike(x, 32.0); |
| 1476 | auto result_le_8 = |
| 1477 | EvaluateChebyshevPolynomial<double>(half * x - two, kI0eCoeffsA); |
| 1478 | auto result_gt_8 = |
| 1479 | EvaluateChebyshevPolynomial<double>(thirty_two / x - two, kI0eCoeffsB) / |
| 1480 | Sqrt(x); |
| 1481 | return Select(Le(x, xla::ScalarLike(x, 8.0)), result_le_8, result_gt_8); |
| 1482 | } |
| 1483 | |
| 1484 | XlaOp BesselI0e(XlaOp x) { |
| 1485 | auto& b = *x.builder(); |