projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 94759b7b TL |
1 | /* |
| 2 | asin(arg) and acos(arg) return the arcsin, arccos, | |
| 3 | respectively of their arguments. | |
| 4 | ||
| 5 | Arctan is called after appropriate range reduction. | |
| 6 | */ | |
| 7 | ||
| 8 | #include <errno.h> | |
| 9 | int errno; | |
| 10 | double atan(); | |
| 11 | double sqrt(); | |
| 12 | static double pio2 = 1.570796326794896619; | |
| 13 | ||
| 14 | double | |
| 15 | asin(arg) double arg; { | |
| 16 | ||
| 17 | double sign, temp; | |
| 18 | ||
| 19 | sign = 1.; | |
| 20 | if(arg <0){ | |
| 21 | arg = -arg; | |
| 22 | sign = -1.; | |
| 23 | } | |
| 24 | ||
| 25 | if(arg > 1.){ | |
| 26 | errno = EDOM; | |
| 27 | return(0.); | |
| 28 | } | |
| 29 | ||
| 30 | temp = sqrt(1. - arg*arg); | |
| 31 | if(arg > 0.7) | |
| 32 | temp = pio2 - atan(temp/arg); | |
| 33 | else | |
| 34 | temp = atan(arg/temp); | |
| 35 | ||
| 36 | return(sign*temp); | |
| 37 | } | |
| 38 | ||
| 39 | double | |
| 40 | acos(arg) double arg; { | |
| 41 | ||
| 42 | if(arg < 0) | |
| 43 | arg = -arg; | |
| 44 | ||
| 45 | if(arg > 1.){ | |
| 46 | errno = EDOM; | |
| 47 | return(0.); | |
| 48 | } | |
| 49 | ||
| 50 | return(pio2 - asin(arg)); | |
| 51 | } |