64 lines
766 B
C++
64 lines
766 B
C++
#include "stdafx.h"
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#include "defs.h"
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void
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eval_arctanh(void)
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{
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push(cadr(p1));
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eval();
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arctanh();
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}
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void
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arctanh(void)
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{
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double d;
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save();
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p1 = pop();
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if (car(p1) == symbol(TANH)) {
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push(cadr(p1));
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restore();
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return;
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}
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if (isdouble(p1)) {
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d = p1->u.d;
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if (d < -1.0 || d > 1.0)
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stop("arctanh function argument is not in the interval [-1,1]");
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d = log((1.0 + d) / (1.0 - d)) / 2.0;
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push_double(d);
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restore();
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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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restore();
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return;
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}
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push_symbol(ARCTANH);
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push(p1);
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list(2);
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restore();
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}
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#if SELFTEST
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static char *s[] = {
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"arctanh(0.0)",
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"0",
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"arctanh(0)",
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"0",
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"arctanh(tanh(x))",
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"x",
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};
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void
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test_arctanh(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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