Runge-Kutta method

# Python3 program to implement Runge
# Kutta method

# A sample differential equation
# "dy/dx = (x - y)/2"
def dydx(x, y) :

	return (x + y - 2);

# Finds value of y for a given x
# using step size h
# and initial value y0 at x0.
def rungeKutta(x0, y0, x, h) :

	# Count number of iterations
	# using step size or
	# step height h
	n = round((x - x0) / h);
	
		# Iterate for number of iterations
	y = y0;
	
	for i in range(1, n + 1) :
		
				# Apply Runge Kutta Formulas
		# to find next value of y
		k1 = h * dydx(x0, y);
		k2 = h * dydx(x0 + 0.5 * h, y + 0.5 * k1);

		# Update next value of y
		y = y + (1.0 / 6.0) * (k1 + 2 * k2);

		# Update next value of x
		x0 = x0 + h;

	return y;

# Driver Code
if __name__ == "__main__" :

	x0 = 0; y = 1;
	x = 2; h = 0.2;

	print("y(x) =",rungeKutta(x0, y, x, h));