Fix neumann quadrature tests

The tests in the targets `spline_quadrature_tests_xperiod_vx` and `spline_quadrature_tests_xnonperiod_vx` all rely on functions called `compute_error`. There are no namespaces to protect these functions so the compiler cannot distinguish between them when linking. As a result some of these functions (including the one for the Neumann quadrature) were not called. This has been fixed by adding anonymous namespaces. The Neumann test has also been fixed. The test case used was symmetric. As a result the errors were machine errors and convergence could not be observed. The new test case is a 5th degree polynomial.

tests/geometryXVx/neumann_quadrature_spline.cpp

@@ -10,6 +10,8 @@
 #include "neumann_spline_quadrature.hpp"
 #include "quadrature.hpp"
 
+namespace {
+
 TEST(NeumannSplineQuadratureTest, ExactForConstantFunc)
 {
     CoordVx const vx_min(0.0);
@@ -56,8 +58,8 @@ double compute_error(int n_elems)
     using IDomainY = ddc::DiscreteDomain<IDimY>;
     using DFieldY = ddc::Chunk<double, IDomainY>;
 
-    ddc::Coordinate<Y<N>> const y_min(0.0);
-    ddc::Coordinate<Y<N>> const y_max(M_PI);
+    ddc::Coordinate<Y<N>> const y_min(-1.0);
+    ddc::Coordinate<Y<N>> const y_max(1.0);
 
     ddc::init_discrete_space<BSplinesY>(y_min, y_max, n_elems);
 
@@ -72,10 +74,11 @@ double compute_error(int n_elems)
     DFieldY values(gridy);
 
     ddc::for_each(gridy, [&](ddc::DiscreteElement<IDimY> const idx) {
-        values(idx) = cos(ddc::coordinate(idx));
+        double x = ddc::coordinate(idx);
+        values(idx) = (x + 1) * (x + 1) * (x + 1) * (x - 1) * (x - 1);
     });
     double integral = integrate(values);
-    return std::abs(2 - integral);
+    return std::abs(16.0 / 15.0 - integral);
 }
 
 template <std::size_t... Is>
@@ -97,3 +100,5 @@ TEST(NeumannSplineQuadratureTest, UniformConverge)
         EXPECT_LE(order_error, 5e-2);
     }
 }
+
+} // namespace

tests/geometryXVx/quadrature.cpp

@@ -7,6 +7,9 @@
 #include "quadrature.hpp"
 #include "simpson_quadrature.hpp"
 #include "trapezoid_quadrature.hpp"
+
+namespace {
+
 struct RDimXPeriod
 {
     static bool constexpr PERIODIC = true;
@@ -169,3 +172,5 @@ TEST(QuadratureTest, SimpsonUniformConverge)
         EXPECT_LE(order_error, 1e-2);
     }
 }
+
+} // namespace

tests/geometryXVx/quadrature_spline.cpp

@@ -9,6 +9,8 @@
 #include "quadrature.hpp"
 #include "spline_quadrature.hpp"
 
+namespace {
+
 TEST(SplineQuadratureTest, ExactForConstantFunc)
 {
     CoordX const x_min(0.0);
@@ -97,3 +99,5 @@ TEST(SplineQuadratureTest, UniformConverge)
         EXPECT_LE(order_error, 5e-2);
     }
 }
+
+} // namespace