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fixed itegration step equation

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This commit is contained in:
Krishna Vedala
2020-06-11 08:46:20 -04:00
parent 3f4b60ea07
commit 5a46e43219
1 changed files with 5 additions and 5 deletions
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10
numerical_methods/ode_midpoint_euler.cpp
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@@ -32,7 +32,7 @@
* dy[0] = y[1];
* dy[1] = mu * (1.f - y[0] * y[0]) * y[1] - y[0];
* ```
* \see ode_midpoint_euler.cpp, ode_semi_implicit_euler.cpp
* \see ode_forward_euler.cpp, ode_semi_implicit_euler.cpp
*/
#include <cmath>
@@ -73,7 +73,10 @@ void exact_solution(const double &x, std::valarray<double> *y) {
*/
/**
* @brief Compute next step approximation using the midpoint-Euler
* method. @f[y_{n+1}=y_n + dx\cdot f\left(x_n,y_n\right)@f]
* method.
* @f[y_{n+1} = y_n + dx\, f\left(x_n+\frac{1}{2}dx,
* y_n + \frac{1}{2}dx\,f\left(x_n,y_n\right)\right)@f]
*
* @param[in] dx step size
* @param[in] x take \f$x_n\f$ and compute \f$x_{n+1}\f$
* @param[in,out] y take \f$y_n\f$ and compute \f$y_{n+1}\f$
@@ -81,9 +84,6 @@ void exact_solution(const double &x, std::valarray<double> *y) {
*/
void midpoint_euler_step(const double dx, const double &x,
std::valarray<double> *y, std::valarray<double> *dy) {
problem(x, y, dy);
y[0] += dy[0] * dx;
problem(x, y, dy);
double tmp_x = x + 0.5 * dx;