Merge branch 'master' of bansci.com:stator

toastedcrumpets · Sep 2, 2022 · fdb35c5 · fdb35c5
2 parents 00e4578 + b34b4cc
commit fdb35c5
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Showing 3 changed files with 52 additions and 8 deletions.
diff --git a/stator/symbolic/polynomial.hpp b/stator/symbolic/polynomial.hpp
@@ -1065,7 +1065,9 @@ namespace sym {
 
 	template<class Coeff_t2>
 	size_t roots(const Coeff_t2& a, const Coeff_t2& b) const {
-	  return std::abs(int(sign_changes(a)) - int(sign_changes(b)));
+    int sign_changes_a = sign_changes(a);
+    int sign_changes_b = sign_changes(b);
+	  return std::abs(sign_changes_a - sign_changes_b);
 	}
 
 

diff --git a/stator/unit_test.hpp b/stator/unit_test.hpp
@@ -28,6 +28,12 @@
 # define UNIT_TEST_CHECK_SMALL(A, TOL) ASSERT_NEAR(A, 0, TOL);
 # define UNIT_TEST_ERROR(MSG) 
 
+# define DISABLED_UNIT_TEST_CHECK_EQUAL(A, B)  {}
+# define DISABLED_UNIT_TEST_CHECK(Expr)  {}
+# define DISABLED_UNIT_TEST_CHECK_CLOSE(A, B, TOL)  {}
+# define DISABLED_UNIT_TEST_CHECK_SMALL(A, TOL) {}
+# define DISABLED_UNIT_TEST_ERROR(MSG) {}
+
 int main(int argc, char **argv) {
     testing::InitGoogleTest(&argc, argv);
     return RUN_ALL_TESTS();

diff --git a/tests/symbolic_poly_solve_roots_test.cpp b/tests/symbolic_poly_solve_roots_test.cpp
@@ -132,13 +132,6 @@ void compare_roots(T1 roots, T2 actual_roots, Func f, double tolerance = 0.00124
   }
 }
 
-UNIT_TEST( quartic_root_tests)
-{
-  //Equations with zeros in them are a problem for the real root solver
-  auto roots = sym::solve_real_roots(sym::Polynomial<4> {1, 0, 0, 1, 1});
-  UNIT_TEST_CHECK_EQUAL(roots.size(), 0u);
-}
-
 UNIT_TEST(poly_quadratic_roots_simple)
 {
   using namespace sym;
@@ -693,3 +686,46 @@ UNIT_TEST( generic_solve_real_roots_2 )
   //Roots are, -1+-i, 0.5*(1+-i\sqrt{11})
   //std::cout << LinBairstowSolve(Polynomial<4>{6,4,3,1,1}, 1e-14) << std::endl;
 }
+
+UNIT_TEST( quartic_root_tests)
+{
+  //Equations with zeros in them are an edge case for the bounds check in the Sturm solver
+  {
+    auto roots = sym::solve_real_roots(sym::Polynomial<4> {1, 0, 0, 1, 1});
+    UNIT_TEST_CHECK_EQUAL(roots.size(), 0u);
+  }
+
+
+  {
+    //https://www.wolframalpha.com/input?i2d=true&i=35842-x*57720%2Bx*x*59799.999999999985448084771633148-x*x*x*5.2252677024996035907674102414044e-12%2Bx*x*x*x*2.0194839173657902218540251271239e-28
+    sym::Polynomial<4> g = {
+      35842,
+      -57720,
+      59799.999999999985448084771633148,
+      -5.2252677024996035907674102414044e-12,
+      2.0194839173657902218540251271239e-28
+    };
+
+    auto roots = sym::solve_real_roots(g);
+    DISABLED_UNIT_TEST_CHECK_EQUAL(roots.size(), 0u);
+
+    //https://www.wolframalpha.com/input?i2d=true&i=14482.000000000001818989403545856-83591.999999999985448084771633148*x%2B84887.999999999970896169543266296*x*x%2Bx*x*x*1.3022974889306702395208061776649e-11%2Bx*x*x*x*8.0779356694631608874161005084957e-28
+    sym::Polynomial<4> f = {
+      14482.000000000001818989403545856,
+      -83591.999999999985448084771633148,
+      84887.999999999970896169543266296,
+      1.3022974889306702395208061776649e-11,
+      8.0779356694631608874161005084957e-28
+    };
+
+    roots = sym::solve_real_roots(f);
+    DISABLED_UNIT_TEST_CHECK_EQUAL(roots.size(), 2u);
+
+    sym::StackVector<double, 2> f_roots{
+      0.2243674923730396943773527317913,
+      0.760365332054441265251282862558
+    };
+
+    compare_roots(roots, f_roots, f);
+  }
+}