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Diffstat (limited to 'src/base/math/asin.c')
-rw-r--r-- | src/base/math/asin.c | 40 |
1 files changed, 40 insertions, 0 deletions
diff --git a/src/base/math/asin.c b/src/base/math/asin.c new file mode 100644 index 0000000..4687715 --- /dev/null +++ b/src/base/math/asin.c @@ -0,0 +1,40 @@ +/* + * asin(arg) and acos(arg) return the arcsin, arccos, + * respectively of their arguments. + * + * Arctan is called after appropriate range reduction. + */ + +#include <u.h> +#include <base.h> + +double +math·asin(double arg) +{ + double temp; + int sign; + + sign = 0; + if(arg < 0) { + arg = -arg; + sign++; + } + if(arg > 1) + return math·NaN(); + temp = math·sqrt(1 - arg*arg); + if(arg > 0.7) + temp = math·PIO2 - math·atan(temp/arg); + else + temp = math·atan(arg/temp); + if(sign) + temp = -temp; + return temp; +} + +double +math·acos(double arg) +{ + if(arg > 1 || arg < -1) + return math·NaN(); + return math·PIO2 - math·asin(arg); +} |