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68ca8c7016
According to enki (bivector community) when there are more than one null vector in a geometry, usually all vectors are null, and it was what to do with multiple null vectors that caused me to balk at using e0 for the null vector. However, using e0 for the null vector makes life much easier, especially as that's what most of the literature does. There are plenty of places, particularly in layout handling, that still need adjustment for the change, but things seem to work (minus duals, but they were broken in the first place, thus the discussion with enki).
37 lines
633 B
R
37 lines
633 B
R
#include "metric.h"
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@implementation Metric
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+(Metric *)R:(int)p, int m, int z
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{
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Metric *metric = [[[Metric alloc] init] autorelease];
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metric.plus = ((1 << p) - 1) << z;
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metric.minus = ((1 << m) - 1) << (z + p);
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metric.zero = (1 << z) - 1;
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return metric;
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}
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static double
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count_minus (unsigned minus)
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{
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double s = 1;
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while (minus) {
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if (minus & 1) {
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s = -s;
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}
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minus >>= 1;
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}
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return s;
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}
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-(double)apply:(unsigned) a, unsigned b
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{
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// find all the squared elements
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unsigned c = a & b;
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// any elements that square to 0 result in 0
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if (c & zero) {
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return 0;
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}
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return count_minus (c & minus);
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}
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@end
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