src/gromacs/math/tests/densityfittingforce.cpp

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  35 /*! \internal \file
  36  * \brief
  37  * Tests for the density fitting force.
  38  *
  39  * \author Christian Blau <blau@kth.se>
  40  * \ingroup module_math
  41  */
  42 #include "gmxpre.h"
  43
  44 #include "gromacs/math/densityfittingforce.h"
  45
  46 #include <gmock/gmock.h>
  47 #include <gtest/gtest.h>
  48
  49 #include "gromacs/math/multidimarray.h"
  50 #include "gromacs/math/utilities.h"
  51 #include "gromacs/math/vec.h"
  52 #include "gromacs/mdspan/extensions.h"
  53
  54 #include "testutils/testasserts.h"
  55 #include "testutils/testmatchers.h"
  56 namespace gmx
  57 {
  58
  59 namespace test
  60 {
  61
  62 namespace
  63 {
  64
  65 TEST(DensityFittingForce, isZeroWhenMatchingDensity)
  66 {
  67     const float         sigma      = 1;
  68     const float         nSigma     = 5;
  69     const RVec          gridCenter = {1, 1, 1};
  70
  71     DensityFittingForce forceEvaluator({{sigma, sigma, sigma}, nSigma});
  72     MultiDimArray<std::vector<float>, dynamicExtents3D> densityDerivative(3, 3, 3);
  73     std::fill(begin(densityDerivative), end(densityDerivative), 0);
  74
  75     const RVec             result   = forceEvaluator.evaluateForce({gridCenter, 1.0}, densityDerivative.asConstView());
  76     const RVec             expected = {0, 0, 0};
  77     FloatingPointTolerance tolerance(defaultFloatTolerance());
  78
  79     EXPECT_FLOAT_EQ_TOL(expected[XX], result[XX], tolerance);
  80     EXPECT_FLOAT_EQ_TOL(expected[YY], result[YY], tolerance);
  81     EXPECT_FLOAT_EQ_TOL(expected[ZZ], result[ZZ], tolerance);
  82 }
  83
  84 TEST(DensityFittingForce, isZeroWhenMismatchingSameAllDirections)
  85 {
  86     const BasicVector<double>  sigma      = {1., 1., 1.};
  87     const float                nSigma     = 5;
  88     const RVec                 gridCenter = {1, 1, 1};
  89
  90     DensityFittingForce        forceEvaluator({{sigma}, nSigma});
  91     MultiDimArray<std::vector<float>, dynamicExtents3D> densityDerivative(3, 3, 3);
  92     std::fill(begin(densityDerivative), end(densityDerivative), 1);
  93
  94     const RVec result   = forceEvaluator.evaluateForce({gridCenter, 1.}, densityDerivative.asConstView());
  95     const RVec expected = {0, 0, 0};
  96
  97     // need to increase the tolerance here, because the checked value is the
  98     // result of a complex calculation (the sum of 27 3d Gaussians weighted with the distance to center)
  99     // \todo increase tightness of this bound with better implementations
 100     FloatingPointTolerance tolerance(absoluteTolerance(1e-8));
 101
 102     EXPECT_FLOAT_EQ_TOL(expected[XX], result[XX], tolerance);
 103     EXPECT_FLOAT_EQ_TOL(expected[YY], result[YY], tolerance);
 104     EXPECT_FLOAT_EQ_TOL(expected[ZZ], result[ZZ], tolerance);
 105 }
 106
 107 TEST(DensityFittingForce, pullsTowardsDerivative)
 108 {
 109     const float         sigma      = 1;
 110     const float         nSigma     = 5;
 111     const RVec          gridCenter = {1, 1, 1};
 112
 113     DensityFittingForce forceEvaluator({{sigma, sigma, sigma}, nSigma});
 114     MultiDimArray<std::vector<float>, dynamicExtents3D> densityDerivative(3, 3, 3);
 115     std::fill(begin(densityDerivative), end(densityDerivative), 0);
 116     densityDerivative(0, 0, 0) = 1;
 117
 118     const RVec result   = forceEvaluator.evaluateForce({gridCenter, 1.}, densityDerivative.asConstView());
 119     real       expected =  -1/sqrt(2*2*2*M_PI*M_PI*M_PI)*exp(-0.5)*exp(-0.5)*exp(-0.5);
 120
 121     EXPECT_FLOAT_EQ(expected, result[XX]);
 122     EXPECT_FLOAT_EQ(expected, result[YY]);
 123     EXPECT_FLOAT_EQ(expected, result[ZZ]);
 124 }
 125
 126 } // namespace
 127
 128 } // namespace test
 129
 130 } // namespace gmx