Mercurial > repos > public > sbplib

comparison +time/Rungekutta.m @ 849:5b180c76578e feature/burgers1d

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Use the old implementation for RK4 until the different methods are profiled.
author Vidar Stiernström <vidar.stiernstrom@it.uu.se>
date Fri, 21 Sep 2018 09:13:03 +0200
parents 1c6f1595bb94
children 4e5e53d6336c
comparison
equal deleted inserted replaced
848:c8ea9bbdc62c 849:5b180c76578e
3 F % RHS of the ODE 3 F % RHS of the ODE
4 k % Time step 4 k % Time step
5 t % Time point 5 t % Time point
6 v % Solution vector 6 v % Solution vector
7 n % Time level 7 n % Time level
8 coeffs % The coefficents used for the RK time integration 8 scheme % The coefficents used for the RK time integration
9 end 9 end
10 10
11 11
12 methods 12 methods
13 % Timesteps v_t = F(v,t), using RK with specfied order from t = t0 with 13 % Timesteps v_t = F(v,t), using RK with specfied order from t = t0 with
17 obj.F = F; 17 obj.F = F;
18 obj.k = k; 18 obj.k = k;
19 obj.t = t0; 19 obj.t = t0;
20 obj.v = v0; 20 obj.v = v0;
21 obj.n = 0; 21 obj.n = 0;
22 % Extract the coefficients for the specified order 22 % TBD: Order 4 is also implemented in the butcher tableau, but the rungekutta_4.m implementation
23 % used for the RK updates from the Butcher tableua. 23 % might be slightly more efficient. Need to do some profiling before deciding whether or not to keep it.
24 [s,a,b,c] = butcherTableau(order); 24 if (order == 4)
25 obj.coeffs = struct('s',s,'a',a,'b',b,'c',c); 25 obj.scheme = @time.rk.rungekutta_4;
26 else
27 % Extract the coefficients for the specified order
28 % used for the RK updates from the Butcher tableua.
29 [s,a,b,c] = time.rk.butcherTableau(order);
30 coeffs = struct('s',s,'a',a,'b',b,'c',c);
31 obj.scheme = @(v,t,dt,F) time.rk.rungekutta(v, t , dt, F, coeffs);
32 end
26 end 33 end
27 34
28 function [v,t] = getV(obj) 35 function [v,t] = getV(obj)
29 v = obj.v; 36 v = obj.v;
30 t = obj.t; 37 t = obj.t;
31 end 38 end
32 39
33 function obj = step(obj) 40 function obj = step(obj)
34 obj.v = time.rk.rungekutta(obj.v, obj.t, obj.k, obj.F, obj.coeffs); 41 obj.v = obj.scheme(obj.v, obj.t, obj.k, obj.F);
35 obj.t = obj.t + obj.k; 42 obj.t = obj.t + obj.k;
36 obj.n = obj.n + 1; 43 obj.n = obj.n + 1;
37 end 44 end
38 end 45 end
39 end 46 end