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