eigenmath/tanh.cpp

56 lines
651 B
C++

// exp(2 x) - 1
// tanh(x) = --------------
// exp(2 x) + 1
#include "stdafx.h"
#include "defs.h"
void
eval_tanh(void)
{
double d;
push(cadr(p1));
eval();
p1 = pop();
if (car(p1) == symbol(ARCTANH)) {
push(cadr(p1));
return;
}
if (isdouble(p1)) {
d = tanh(p1->u.d);
if (fabs(d) < 1e-10)
d = 0.0;
push_double(d);
return;
}
if (iszero(p1)) {
push(zero);
return;
}
push_symbol(TANH);
push(p1);
list(2);
}
#if SELFTEST
static char *s[] = {
"tanh(x)",
"tanh(x)",
"tanh(0)",
"0",
"tanh(arctanh(x))",
"x",
};
void
test_tanh(void)
{
test(__FILE__, s, sizeof s / sizeof (char *));
}
#endif