projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| e804469b | 1 | /* @(#)asin.c 4.1 12/25/82 */ |
| c8c4d6b2 SL |
2 | |
| 3 | /* | |
| 4 | asin(arg) and acos(arg) return the arcsin, arccos, | |
| 5 | respectively of their arguments. | |
| 6 | ||
| 7 | Arctan is called after appropriate range reduction. | |
| 8 | */ | |
| 9 | ||
| 10 | #include <errno.h> | |
| 11 | int errno; | |
| 12 | double atan(); | |
| 13 | double sqrt(); | |
| 14 | static double pio2 = 1.570796326794896619; | |
| 15 | ||
| 16 | double | |
| 17 | asin(arg) double arg; { | |
| 18 | ||
| 19 | double sign, temp; | |
| 20 | ||
| 21 | sign = 1.; | |
| 22 | if(arg <0){ | |
| 23 | arg = -arg; | |
| 24 | sign = -1.; | |
| 25 | } | |
| 26 | ||
| 27 | if(arg > 1.){ | |
| 28 | errno = EDOM; | |
| 29 | return(0.); | |
| 30 | } | |
| 31 | ||
| 32 | temp = sqrt(1. - arg*arg); | |
| 33 | if(arg > 0.7) | |
| 34 | temp = pio2 - atan(temp/arg); | |
| 35 | else | |
| 36 | temp = atan(arg/temp); | |
| 37 | ||
| 38 | return(sign*temp); | |
| 39 | } | |
| 40 | ||
| 41 | double | |
| 42 | acos(arg) double arg; { | |
| 43 | ||
| 44 | if((arg > 1.) || (arg < -1.)){ | |
| 45 | errno = EDOM; | |
| 46 | return(0.); | |
| 47 | } | |
| 48 | ||
| 49 | return(pio2 - asin(arg)); | |
| 50 | } |