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- #include <u.h>
- #include <libc.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
- tanh(double arg)
- {
- if(arg < 0) {
- arg = -arg;
- if(arg > 21)
- return -1;
- return -sinh(arg)/cosh(arg);
- }
- if(arg > 21)
- return 1;
- return sinh(arg)/cosh(arg);
- }
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