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cargo fmt

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This commit is contained in:
Jorge Aparicio 2018-07-17 19:46:12 -05:00
parent 1c555103ae
commit 9f920e739a
1 changed files with 48 additions and 49 deletions
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97
library/compiler-builtins/libm/src/math/pow.rs
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@ -9,55 +9,54 @@
* ====================================================
*/
/// pow(x,y) return x**y
///
/// n
/// Method: Let x = 2 * (1+f)
/// 1. Compute and return log2(x) in two pieces:
/// log2(x) = w1 + w2,
/// where w1 has 53-24 = 29 bit trailing zeros.
/// 2. Perform y*log2(x) = n+y' by simulating muti-precision
/// arithmetic, where |y'|<=0.5.
/// 3. Return x**y = 2**n*exp(y'*log2)
///
/// Special cases:
/// 1. (anything) ** 0 is 1
/// 2. 1 ** (anything) is 1
/// 3. (anything except 1) ** NAN is NAN
/// 4. NAN ** (anything except 0) is NAN
/// 5. +-(|x| > 1) ** +INF is +INF
/// 6. +-(|x| > 1) ** -INF is +0
/// 7. +-(|x| < 1) ** +INF is +0
/// 8. +-(|x| < 1) ** -INF is +INF
/// 9. -1 ** +-INF is 1
/// 10. +0 ** (+anything except 0, NAN) is +0
/// 11. -0 ** (+anything except 0, NAN, odd integer) is +0
/// 12. +0 ** (-anything except 0, NAN) is +INF, raise divbyzero
/// 13. -0 ** (-anything except 0, NAN, odd integer) is +INF, raise divbyzero
/// 14. -0 ** (+odd integer) is -0
/// 15. -0 ** (-odd integer) is -INF, raise divbyzero
/// 16. +INF ** (+anything except 0,NAN) is +INF
/// 17. +INF ** (-anything except 0,NAN) is +0
/// 18. -INF ** (+odd integer) is -INF
/// 19. -INF ** (anything) = -0 ** (-anything), (anything except odd integer)
/// 20. (anything) ** 1 is (anything)
/// 21. (anything) ** -1 is 1/(anything)
/// 22. (-anything) ** (integer) is (-1)**(integer)*(+anything**integer)
/// 23. (-anything except 0 and inf) ** (non-integer) is NAN
///
/// Accuracy:
/// pow(x,y) returns x**y nearly rounded. In particular
/// pow(integer,integer)
/// always returns the correct integer provided it is
/// representable.
///
/// Constants :
/// The hexadecimal values are the intended ones for the following
/// constants. The decimal values may be used, provided that the
/// compiler will convert from decimal to binary accurately enough
/// to produce the hexadecimal values shown.
///
// pow(x,y) return x**y
//
// n
// Method: Let x = 2 * (1+f)
// 1. Compute and return log2(x) in two pieces:
// log2(x) = w1 + w2,
// where w1 has 53-24 = 29 bit trailing zeros.
// 2. Perform y*log2(x) = n+y' by simulating muti-precision
// arithmetic, where |y'|<=0.5.
// 3. Return x**y = 2**n*exp(y'*log2)
//
// Special cases:
// 1. (anything) ** 0 is 1
// 2. 1 ** (anything) is 1
// 3. (anything except 1) ** NAN is NAN
// 4. NAN ** (anything except 0) is NAN
// 5. +-(|x| > 1) ** +INF is +INF
// 6. +-(|x| > 1) ** -INF is +0
// 7. +-(|x| < 1) ** +INF is +0
// 8. +-(|x| < 1) ** -INF is +INF
// 9. -1 ** +-INF is 1
// 10. +0 ** (+anything except 0, NAN) is +0
// 11. -0 ** (+anything except 0, NAN, odd integer) is +0
// 12. +0 ** (-anything except 0, NAN) is +INF, raise divbyzero
// 13. -0 ** (-anything except 0, NAN, odd integer) is +INF, raise divbyzero
// 14. -0 ** (+odd integer) is -0
// 15. -0 ** (-odd integer) is -INF, raise divbyzero
// 16. +INF ** (+anything except 0,NAN) is +INF
// 17. +INF ** (-anything except 0,NAN) is +0
// 18. -INF ** (+odd integer) is -INF
// 19. -INF ** (anything) = -0 ** (-anything), (anything except odd integer)
// 20. (anything) ** 1 is (anything)
// 21. (anything) ** -1 is 1/(anything)
// 22. (-anything) ** (integer) is (-1)**(integer)*(+anything**integer)
// 23. (-anything except 0 and inf) ** (non-integer) is NAN
//
// Accuracy:
// pow(x,y) returns x**y nearly rounded. In particular
// pow(integer,integer)
// always returns the correct integer provided it is
// representable.
//
// Constants :
// The hexadecimal values are the intended ones for the following
// constants. The decimal values may be used, provided that the
// compiler will convert from decimal to binary accurately enough
// to produce the hexadecimal values shown.
//
use super::{fabs, get_high_word, scalbn, sqrt, with_set_high_word, with_set_low_word};
const BP: [f64; 2] = [1.0, 1.5];