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[qfcc] Implement mutli-vector division
But only for scalar divisors. The simple method of AB†/(BB†) works only if B is a versor and there's also the problem of left and right division. Thanks to sudgy for making me stop and think before I actually implemented anything (though he mentioned only that it doesn't work for general mutli-vector divisors).
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2 changed files with 42 additions and 1 deletions
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@ -1374,7 +1374,37 @@ commutator_product (expr_t *e1, expr_t *e2)
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static expr_t *
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multivector_divide (expr_t *e1, expr_t *e2)
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{
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internal_error (e1, "not implemented");
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if (is_algebra (get_type (e2))) {
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return error (e2, "Division is left-right ambiguous (and works only"
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" for versors anyway). Use explicit reversion and divide"
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" by square magnitude instead.");
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}
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if (!is_algebra (get_type (e1))) {
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internal_error (e1, "wtw?");
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}
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auto t1 = get_type (e1);
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auto algebra = algebra_get (t1);
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auto layout = &algebra->layout;
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auto stype = algebra->type;
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expr_t *a[layout->count] = {};
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e1 = mvec_expr (e1, algebra);
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e2 = promote_scalar (algebra->type, e2);
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mvec_scatter (a, e1, algebra);
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for (int i = 0; i < layout->count; i++) {
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if (!a[i]) {
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continue;
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}
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auto den = e2;
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auto ct = get_type (a[i]);
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int width = type_width (ct);
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if (width > 1) {
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den = new_extend_expr (den, vector_type (stype, width), 2, false);
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}
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a[i] = new_binary_expr ('/', a[i], den);
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a[i]->e.expr.type = ct;
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}
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return mvec_gather (a, algebra);
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}
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expr_t *
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@ -230,5 +230,16 @@ main (void)
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s.scalar, s.bvec);
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return 1;
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}
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e.mvec = e.mvec / 2; // odd
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if ((dvec3)e.vec != '2 3 0.5'd || (scalar_t)e.tvec != -10) {
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printf ("odd† != '2 3 0.5' + -10: %lv %g\n", e.vec, e.tvec);
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return 1;
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}
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s.mvec = s.mvec / 2; // even
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if (s.scalar != -4.5 || (dvec3)s.bvec != '-7 -22 -23'd) {
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printf ("even† != -4.5, '-7 -22 -23': %g %lv\n",
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s.scalar, s.bvec);
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return 1;
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}
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return 0; // to survive and prevail :)
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}
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