53 lines
1.1 KiB
C++
53 lines
1.1 KiB
C++
#include <iostream>
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#include <sstream>
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#include <vector>
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#include <lapacke.h>
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using namespace std;
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int main()
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{
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int n = 10;
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unsigned int nodes = n+1;
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int rhs = 1;
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double a = 1.0;
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double alpha = 2.0;
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double gB = 1.0;
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double d = n + a/3.0/n;
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double s = - n + a / 6.0 / n;
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cout << d << endl;
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cout << s << endl;
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//Lapacke overwrites upper/lower diagonal so store twice
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vector<double> upperdiagonal(n,s);
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vector<double> lowerdiagonal(n,s);
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vector<double> diagonal(nodes,2*d);
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vector<double> F(nodes,1.0/n);
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diagonal[0]=1.0;
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diagonal[n]=d+alpha;
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upperdiagonal[0] = 0.0;
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//
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F[0] = 0;
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F[n]= 1.0/n/2.0 +alpha*gB;
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//Tridiagonal
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LAPACKE_dgtsv(LAPACK_COL_MAJOR,nodes,rhs,lowerdiagonal.data(),diagonal.data(),upperdiagonal.data(),F.data(),nodes);
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cout << "Solution u_h at nodes x_1..x_" << n << ":\n";
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for (unsigned int i = 0; i < nodes; ++i) {
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double xi = double(i) /double(n);
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cout << "u_h(" << xi << ") = " << F[i] << "\n";
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// F will be overwritten with sol
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}
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return 0;
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}
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