57 lines
1.2 KiB
C++
57 lines
1.2 KiB
C++
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#include <iostream>
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#include <Eigen/Core>
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using namespace Eigen;
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#ifndef SCALAR
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#define SCALAR float
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#endif
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#ifndef SIZE
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#define SIZE 10000
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#endif
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#ifndef REPEAT
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#define REPEAT 10000
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#endif
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typedef Matrix<SCALAR, Eigen::Dynamic, 1> Vec;
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using namespace std;
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SCALAR E_VDW(const Vec &interactions1, const Vec &interactions2)
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{
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return (interactions2.cwise()/interactions1)
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.cwise().cube()
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.cwise().square()
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.cwise().square()
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.sum();
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}
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int main()
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{
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//
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// 1 2 3 4 ... (interactions)
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// ka . . . . ...
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// rab . . . . ...
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// energy . . . . ...
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// ... ... ... ... ... ...
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// (variables
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// for
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// interaction)
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//
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Vec interactions1(SIZE), interactions2(SIZE); // SIZE is the number of vdw interactions in our system
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// SetupCalculations()
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SCALAR rab = 1.0;
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interactions1.setConstant(2.4);
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interactions2.setConstant(rab);
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// Energy()
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SCALAR energy = 0.0;
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for (unsigned int i = 0; i<REPEAT; ++i) {
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energy += E_VDW(interactions1, interactions2);
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energy *= 1 + 1e-20 * i; // prevent compiler from optimizing the loop
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}
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cout << "energy = " << energy << endl;
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}
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