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corrected semi-implicit euler function

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This commit is contained in:
Krishna Vedala
2020-06-11 12:28:19 -04:00
parent 20d7a6b6f2
commit 11689f4312
1 changed files with 5 additions and 7 deletions
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12
numerical_methods/ode_semi_implicit_euler.cpp
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@@ -82,14 +82,12 @@ void exact_solution(const double &x, std::valarray<double> *y) {
void semi_implicit_euler_step(const double dx, const double &x,
std::valarray<double> *y,
std::valarray<double> *dy) {
problem(x, y, dy);
double tmp_x = x + 0.5 * dx;
problem(x, y, dy); // update dy once
y[0][0] += dx * dy[0][0]; // update y0
problem(x, y, dy); // update dy once more
std::valarray<double> tmp_y = y[0] + dy[0] * (0.5 * dx);
problem(tmp_x, &tmp_y, dy);
y[0] += dy[0] * dx;
dy[0][0] = 0.f; // ignore y0
y[0] += dy[0] * dx; // update remaining using new dy
}
/**