167 lines
1.9 KiB
C++
167 lines
1.9 KiB
C++
#include "stdafx.h"
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#include "defs.h"
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void
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eval_arcsin(void)
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{
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push(cadr(p1));
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eval();
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yyarcsin();
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}
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void
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arcsin(void)
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{
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save();
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yyarcsin();
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restore();
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}
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void
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yyarcsin(void)
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{
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int n;
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double d;
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p1 = pop();
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if (car(p1) == symbol(SIN)) {
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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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errno = 0;
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d = asin(p1->u.d);
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if (errno)
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stop("arcsin function argument is not in the interval [-1,1]");
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push_double(d);
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return;
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}
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// if p1 == 1/sqrt(2) then return 1/4*pi (45 degrees)
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if (isoneoversqrttwo(p1)) {
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push_rational(1, 4);
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push_symbol(PI);
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multiply();
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return;
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}
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// if p1 == -1/sqrt(2) then return -1/4*pi (-45 degrees)
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if (isminusoneoversqrttwo(p1)) {
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push_rational(-1, 4);
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push_symbol(PI);
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multiply();
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return;
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}
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if (!isrational(p1)) {
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push_symbol(ARCSIN);
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push(p1);
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list(2);
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return;
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}
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push(p1);
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push_integer(2);
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multiply();
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n = pop_integer();
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switch (n) {
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case -2:
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push_rational(-1, 2);
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push_symbol(PI);
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multiply();
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break;
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case -1:
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push_rational(-1, 6);
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push_symbol(PI);
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multiply();
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break;
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case 0:
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push(zero);
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break;
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case 1:
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push_rational(1, 6);
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push_symbol(PI);
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multiply();
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break;
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case 2:
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push_rational(1, 2);
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push_symbol(PI);
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multiply();
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break;
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default:
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push_symbol(ARCSIN);
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push(p1);
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list(2);
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break;
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}
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}
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#if SELFTEST
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static char *s[] = {
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"arcsin(-1)",
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"-1/2*pi",
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"arcsin(-1/2)",
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"-1/6*pi",
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"arcsin(0)",
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"0",
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"arcsin(1/2)",
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"1/6*pi",
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"arcsin(1)",
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"1/2*pi",
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"arcsin(sin(-1/2*pi))",
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"-1/2*pi",
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"arcsin(sin(-1/6*pi))",
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"-1/6*pi",
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"arcsin(sin(0))",
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"0",
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"arcsin(sin(1/6*pi))",
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"1/6*pi",
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"arcsin(sin(1/2*pi))",
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"1/2*pi",
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"arcsin(sin(x))",
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"x",
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"arcsin(1/sqrt(2))",
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"1/4*pi",
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"arcsin(-1/sqrt(2))",
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"-1/4*pi",
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"arcsin(sin(1/4*pi))",
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"1/4*pi",
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"arcsin(sin(-1/4*pi))",
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"-1/4*pi",
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};
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void
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test_arcsin(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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