Implicit Methods for Linear and Nonlinear Systems of ODEs
web.mit.edu › 16 › BackUpUsually, the initial guess for vn+1 is the previous iteration, i.e. w0 =vn. So, the entire iteration from n to n+1 has the following form, 1. Set initial guess: w0 =vn and m =0. 2. Calculate residual R(wm)and linearization ∂R/∂w|wm. 3. Solve Equation 73 for ∆w. 4. Update wm+1 =wm +∆w. 5. Check if R(wm+1)is small. If not, set m ←m+1 and repeat steps 1 through 4.
MATH2071: LAB 9: Implicit ODE methods
www.math.pitt.edu › ~sussmanm › 2071Spring09from which you can see that this is also an ``implicit'' formula. The backward Euler and Trapezoid methods are the first two members of the ``Adams-Moulton'' family of ODE solvers. In the exercise below, you will write a version of the trapezoid method using Newton's method to solve the per-timestep equation, just as with back_euler. As you will see in later exercises, the trapezoid method is not so appropriate when the equation gets very stiff, and Newton's method is overkill when the ...