diff options
Diffstat (limited to 'src/base/math/tanh.c')
-rw-r--r-- | src/base/math/tanh.c | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/src/base/math/tanh.c b/src/base/math/tanh.c new file mode 100644 index 0000000..81e428a --- /dev/null +++ b/src/base/math/tanh.c @@ -0,0 +1,25 @@ +#include <u.h> +#include <base.h> + +/* + tanh(arg) computes the hyperbolic tangent of its floating + point argument. + + sinh and cosh are called except for large arguments, which + would cause overflow improperly. + */ + +double +math·tanh(double arg) +{ + + if(arg < 0) { + arg = -arg; + if(arg > 21) + return -1; + return -math·sinh(arg)/math·cosh(arg); + } + if(arg > 21) + return 1; + return math·sinh(arg)/math·cosh(arg); +} |