157 lines
1.8 KiB
C++
157 lines
1.8 KiB
C++
// Absolute value, aka vector magnitude
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#include "stdafx.h"
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#include "defs.h"
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static void yyabsval(void);
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static void absval_tensor(void);
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void
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eval_abs(void)
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{
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push(cadr(p1));
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eval();
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absval();
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}
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void
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absval(void)
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{
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save();
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yyabsval();
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restore();
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}
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static void
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yyabsval(void)
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{
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int h;
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p1 = pop();
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if (istensor(p1)) {
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absval_tensor();
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return;
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}
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if (isnum(p1)) {
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push(p1);
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if (isnegativenumber(p1))
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negate();
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return;
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}
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if (iscomplexnumber(p1)) {
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push(p1);
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push(p1);
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conjugate();
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multiply();
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push_rational(1, 2);
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power();
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return;
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}
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// abs(1/a) evaluates to 1/abs(a)
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if (car(p1) == symbol(POWER) && isnegativeterm(caddr(p1))) {
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push(p1);
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reciprocate();
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absval();
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reciprocate();
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return;
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}
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// abs(a*b) evaluates to abs(a)*abs(b)
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if (car(p1) == symbol(MULTIPLY)) {
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h = tos;
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p1 = cdr(p1);
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while (iscons(p1)) {
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push(car(p1));
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absval();
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p1 = cdr(p1);
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}
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multiply_all(tos - h);
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return;
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}
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if (isnegativeterm(p1) || (car(p1) == symbol(ADD) && isnegativeterm(cadr(p1)))) {
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push(p1);
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negate();
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p1 = pop();
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}
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push_symbol(ABS);
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push(p1);
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list(2);
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}
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static void
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absval_tensor(void)
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{
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if (p1->u.tensor->ndim != 1)
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stop("abs(tensor) with tensor rank > 1");
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push(p1);
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push(p1);
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conjugate();
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inner();
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push_rational(1, 2);
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power();
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}
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static char *s[] = {
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"abs(2)",
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"2",
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"abs(2.0)",
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"2",
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"abs(-2)",
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"2",
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"abs(-2.0)",
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"2",
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"abs(a)",
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"abs(a)",
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"abs(-a)",
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"abs(a)",
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"abs(2*a)",
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"2*abs(a)",
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"abs(-2*a)",
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"2*abs(a)",
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"abs(2.0*a)",
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"2*abs(a)",
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"abs(-2.0*a)",
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"2*abs(a)",
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"abs(a-b)+abs(b-a)",
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"2*abs(a-b)",
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"abs(3 + 4 i)",
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"5",
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"abs((2,3,4))",
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"29^(1/2)",
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"abs(a*b)",
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"abs(a)*abs(b)",
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"abs(a/b)",
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"abs(a)/abs(b)",
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"abs(1/a^b)",
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"1/(abs(a^b))",
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};
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void
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test_abs(void)
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{
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test(__FILE__, s, sizeof s / sizeof (char *));
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}
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