I solved differential equations in c++ using euler method. In output i got only few values after that it is giving nan values. Is there any problem in the code or method can't solve those stiff equations.
I am not an expert, but it sounds like a method problem to me or probably something wrong when coding your algorithm. Maybe this paper can help you: http://www.lehman.edu/academics/cmacs/documents/NumericalIntegrationTutorial.pdf
Euler method is the simpliest method for solving differential equations. But it isn't clear how to help you without more information. Of course this can be because of mistake coding or maybe you are calculating with big iteration step. What kind of diffenertial equations you solve? What kind of boundary conditions you use?
There are many C++ libraries that already provide implemented algorithms to resolve ordinary differential equations among which odeint (see link 1 and 2).
You can find other numerical libraries for C++ at the link 3.
Other sources on the application of Euler method to solve differential equations in link 4 and 5.
http://headmyshoulder.github.io/odeint-v2/
https://en.wikipedia.org/wiki/List_of_numerical_libraries#C.2B.2B
http://rosettacode.org/wiki/Euler_method#C.2B.2B
http://www.codeproject.com/Articles/43607/Solving-ordinary-differential-equations-in-C
Article Odeint – Solving Ordinary Differential Equations in C++
Hey, I'm not a pro programmer, However, This code work correctly :
/*
Consider below differential equation
dy/dx = (x + y + xy)
with initial condition y(0) = 1
and step size h = 0.025.
Find y(0.1).
Solution:
f(x, y) = (x + y + xy)
x0 = 0, y0 = 1, h = 0.025
Now we can calculate y1 using Euler formula
y1 = y0 + h * f(x0, y0)
y1 = 1 + 0.025 *(0 + 1 + 0 * 1)
y1 = 1.025
y(0.025) = 1.025.
Similarly we can calculate y(0.050), y(0.075), ....y(0.1).
y(0.1) = 1.11167
*/
/* CPP Program to find approximation
of a ordinary differential equation
using euler method.*/
#include
using namespace std;
// Consider a differential equation
// dy/dx=(x + y + xy)
float func(float x, float y)
{
return (x + y + x * y);
}
// Function for Euler formula
void euler(float x0, float y, float h, float x)
{
float temp = -0;
// Iterating till the point at which we
// need approximation
while (x0 < x) {
temp = y;
y = y + h * func(x0, y);
x0 = x0 + h;
}
// Printing approximation
cout
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