147 lines
1.8 KiB
C++
147 lines
1.8 KiB
C++
//-----------------------------------------------------------------------------
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//
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// Author : philippe.billet@noos.fr
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//
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// sgn sign function
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//
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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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static void ysgn(void);
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static int iscomplexnumber(U *);
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extern int isnegativeterm(U *);
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void
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eval_sgn(void)
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{
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push(cadr(p1));
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eval();
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sgn();
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}
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void
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sgn(void)
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{
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save();
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ysgn();
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restore();
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}
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#define X p1
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void
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ysgn(void)
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{
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X = pop();
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if (p1->k == DOUBLE) {
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if (p1->u.d > 0)
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{push_integer(1);
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return;}
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else
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if (p1->u.d == 0)
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{push_integer(1);
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return;}
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else
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{push_integer(-1);
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return;}
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}
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if (p1->k == NUM) {
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if (MSIGN(mmul(p1->u.q.a,p1->u.q.b)) == -1)
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{push_integer(-1);
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return;}
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else
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if (MZERO(mmul(p1->u.q.a,p1->u.q.b)))
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{push_integer(0);
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return;}
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else
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{push_integer(1);
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return;}
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}
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if (iscomplexnumber(X)){
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push_integer(-1);
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push(X);
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absval();
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power();
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push(X);
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multiply();
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return;
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}
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if (isnegativeterm(X)) {
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push_symbol(SGN);
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push(X);
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negate();
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list(2);
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push_integer(-1);
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multiply();
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return;
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}
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/* push_integer(2);
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push(X);
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heaviside();
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multiply();
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push_integer(-1);
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add(); */
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push_symbol(SGN);
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push(X);
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list(2);
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}
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static int
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iscomplex(U *p)
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{
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if (car(p) == symbol(POWER) && isminusone(cadr(p)))
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return 1;
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if (iscons(p)) {
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while (iscons(p)) {
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if (iscomplex(car(p)))
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return 1;
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p = cdr(p);
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}
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}
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return 0;
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}
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static int
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iscomplexnumber(U *p)
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{
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if (iscomplex(p) && !issymbolic(p))
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return 1;
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else
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return 0;
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}
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static char *s[] = {
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"sgn(-3)",
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"-1",
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"sgn(0)",
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"0",
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"sgn(3)",
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"1",
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};
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void
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test_sgn(void)
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{
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test(__FILE__, s, sizeof s / sizeof (char *));
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}
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