85 lines
1.0 KiB
C++
85 lines
1.0 KiB
C++
//-----------------------------------------------------------------------------
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//
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// exp(x) + exp(-x)
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// cosh(x) = ----------------
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// 2
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//
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//-----------------------------------------------------------------------------
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#include "stdafx.h"
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#include "defs.h"
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void ycosh(void);
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static void yycosh(void);
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void
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eval_cosh(void)
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{
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push(cadr(p1));
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eval();
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ycosh();
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}
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void
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ycosh(void)
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{
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save();
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yycosh();
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restore();
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}
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static void
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yycosh(void)
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{
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double d;
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p1 = pop();
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if (p1->k == DOUBLE) {
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d = cosh(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 (expomode == 1) {
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push(p1);
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exponential();
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push(p1);
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negate();
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exponential();
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add();
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push_rational(1, 2);
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multiply();
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return;
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}
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if (iszero(p1)) {
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push(one);
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return;
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}
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push_symbol(COSH);
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push(p1);
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list(2);
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}
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static char *s[] = {
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"cosh(x)",
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"cosh(x)",
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"cosh(0)",
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"1",
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"expomode=1",
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"",
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"cosh(x)",
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"1/2*exp(x)+1/2*exp(-x)",
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"expomode=0",
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"",
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};
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void
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test_cosh(void)
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{
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test(__FILE__, s, sizeof s / sizeof (char *));
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}
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