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trkstep.cpp - numeric - C++ library with numerical algorithms |
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git clone git://src.adamsgaard.dk/numeric |
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trkstep.cpp (541B) |
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1 #include <stdlib.h> |
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2 #include <cmath> |
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3 #include <vector> |
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4 |
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5 using namespace std; |
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6 |
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7 // Stepper function |
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8 void rkstep( |
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9 void f(int, double, vector<double>*, vector<double>*), |
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10 int n, double t, vector<double>* y, double h, vector<double>* y1… |
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11 { |
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12 vector<double> k0(n); |
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13 vector<double> y12(n); |
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14 vector<double> k12(n); |
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15 (*f)(n,t,y,&k0); |
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16 for(int i = 0;i<n;i++) y12[i] = (*y)[i]+k0[i]*h/2; |
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17 (*f)(n,(t+h/2),&y12,&k12); |
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18 for(int i = 0;i<n;i++) (*y1)[i] = (*y)[i]+k12[i]*h; |
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19 for(int i = 0;i<n;i++) (*dy)[i] = (k0[i]-k12[i])*1*(h)/2; |
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20 }; |
