Invalid example for spintracing

[Krzmbrzl]

In

SeQuant/tests/unit/test_spin.cpp

Lines 279 to 285 in 7f31851

	const auto expr =
	ex<Constant>(rational{1, 2}) *
	ex<Tensor>(L"g", WstrList{L"i_1", L"i_2"}, WstrList{L"a_1", L"a_2"},
	Symmetry::antisymm) *
	ex<Tensor>(L"t", WstrList{L"a_1"}, WstrList{L"i_1"}) *
	ex<Tensor>(L"t", WstrList{L"a_2"}, WstrList{L"i_2"});
	auto result = spintrace(expr, {{L"i_1", L"a_1"}});

the spintrace function is fed the given expression with the information that i_1 and a_1 are external indices that belong to a single particle (group). However, the given expression is a full contraction leading to a scalar and thus the expression doesn't have any external indices. Therefore, I believe that this test case doesn't make sense in its current form 🤔

[Krzmbrzl]

Actually, it seems that this issue is present in the entire block

SeQuant/tests/unit/test_spin.cpp

Lines 267 to 326 in 7f31851

	SECTION("Product") {
	const auto expr = ex<Tensor>(L"f", WstrList{L"i_1"}, WstrList{L"a_1"}) *
	ex<Tensor>(L"t", WstrList{L"a_1"}, WstrList{L"i_1"});
	auto result = spintrace(expr, {{L"i_1", L"a_1"}});
	canonicalize(result);
	REQUIRE(to_latex(result) ==
	L"{ \\bigl({{{2}}{f^{{a_1}}_{{i_1}}}{t^{{i_1}}_{{a_1}}}}\\bigr) }");
	}
	SECTION("Scaled Product") {
	{
	// 1/2 * g * t1 * t1
	const auto expr =
	ex<Constant>(rational{1, 2}) *
	ex<Tensor>(L"g", WstrList{L"i_1", L"i_2"}, WstrList{L"a_1", L"a_2"},
	Symmetry::antisymm) *
	ex<Tensor>(L"t", WstrList{L"a_1"}, WstrList{L"i_1"}) *
	ex<Tensor>(L"t", WstrList{L"a_2"}, WstrList{L"i_2"});
	auto result = spintrace(expr, {{L"i_1", L"a_1"}});
	canonicalize(result);
	REQUIRE(
	to_latex(result) ==
	L"{ \\bigl( - "
	L"{{g^{{a_1}{a_2}}_{{i_1}{i_2}}}{t^{{i_2}}_{{a_1}}}{t^{{i_1}}_{"
	L"{a_2}}}} + "
	L"{{{2}}{g^{{a_1}{a_2}}_{{i_1}{i_2}}}{t^{{i_1}}_{{a_1}}}{t^{{i_2}}_{"
	L"{a_2}}}}\\bigr) }");
	}
	}
	SECTION("Sum") {
	// f * t1 + 1/2 * g * t1 * t1 + 1/4 * g * t2
	const auto ex1 = ex<Tensor>(L"f", WstrList{L"i_1"}, WstrList{L"a_1"}) *
	ex<Tensor>(L"t", WstrList{L"a_1"}, WstrList{L"i_1"});
	const auto ex2 = ex<Constant>(rational{1, 2}) *
	ex<Tensor>(L"g", WstrList{L"i_1", L"i_2"},
	WstrList{L"a_1", L"a_2"}, Symmetry::antisymm) *
	ex<Tensor>(L"t", WstrList{L"a_1"}, WstrList{L"i_1"}) *
	ex<Tensor>(L"t", WstrList{L"a_2"}, WstrList{L"i_2"});
	const auto ex3 = ex<Constant>(rational{1, 4}) *
	ex<Tensor>(L"g", WstrList{L"i_1", L"i_2"},
	WstrList{L"a_1", L"a_2"}, Symmetry::antisymm) *
	ex<Tensor>(L"t", WstrList{L"a_1", L"a_2"},
	WstrList{L"i_1", L"i_2"}, Symmetry::antisymm);
	auto expr = ex1 + ex2 + ex3;
	auto result = ex<Constant>(rational{1, 2}) * spintrace(expr);
	expand(result);
	rapid_simplify(result);
	canonicalize(result);
	REQUIRE(to_latex(result) ==
	L"{ \\bigl({{f^{{a_1}}_{{i_1}}}{t^{{i_1}}_{{a_1}}}} + "
	L"{{g^{{a_1}{a_2}}_{{i_1}{i_2}}}{t^{{i_1}{i_2}}_{{a_1}{a_2}}}} - "
	L"{{{\\frac{1}{2}}}{g^{{a_1}{a_2}}_{{i_1}{i_2}}}{t^{{i_2}{i_1}}_{{"
	L"a_1}{a_2}}}} - "
	L"{{{\\frac{1}{2}}}{g^{{a_1}{a_2}}_{{i_1}{i_2}}}{t^{{i_2}}_{{a_1}}}"
	L"{t^{{i_1}}_{{a_2}}}} + "
	L"{{g^{{a_1}{a_2}}_{{i_1}{i_2}}}{t^{{i_1}}_{{a_1}}}{t^{{i_2}}_{{a_"
	L"2}}}}\\bigr) }");
	} // Sum