67 lines
1.0 KiB
C++
67 lines
1.0 KiB
C++
#include "stdafx.h"
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#include "defs.h"
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void
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eval_degree(void)
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{
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push(cadr(p1));
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eval();
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push(caddr(p1));
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eval();
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p1 = pop();
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if (p1 == symbol(NIL))
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guess();
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else
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push(p1);
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degree();
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}
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//-----------------------------------------------------------------------------
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//
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// Find the degree of a polynomial
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//
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// Input: tos-2 p(x)
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//
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// tos-1 x
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//
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// Output: Result on stack
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//
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// Note: Finds the largest numerical power of x. Does not check for
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// weirdness in p(x).
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//
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//-----------------------------------------------------------------------------
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#define POLY p1
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#define X p2
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#define DEGREE p3
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void
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degree(void)
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{
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save();
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X = pop();
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POLY = pop();
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DEGREE = zero;
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yydegree(POLY);
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push(DEGREE);
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restore();
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}
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void
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yydegree(U *p)
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{
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if (equal(p, X)) {
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if (iszero(DEGREE))
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DEGREE = one;
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} else if (car(p) == symbol(POWER)) {
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if (equal(cadr(p), X) && isnum(caddr(p)) && lessp(DEGREE, caddr(p)))
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DEGREE = caddr(p);
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} else if (iscons(p)) {
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p = cdr(p);
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while (iscons(p)) {
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yydegree(car(p));
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p = cdr(p);
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}
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}
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}
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