Mercurial > repos > public > sbplib
view +time/+rk/butcherTableau.m @ 1037:2d7ba44340d0 feature/burgers1d
Pass scheme specific parameters as cell array. This will enabale constructDiffOps to be more general. In addition, allow for schemes returning function handles as diffOps, which is currently how non-linear schemes such as Burgers1d are implemented.
author | Vidar Stiernström <vidar.stiernstrom@it.uu.se> |
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date | Fri, 18 Jan 2019 09:02:02 +0100 |
parents | e0560bc4fb7d |
children |
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function [s,a,b,c] = butcherTableau(order) % TODO: Change order from a double to string. switch order case 3 % TVD (Total Variational Diminishing) s = 3; a = zeros(s,s-1); a(2,1) = 1; a(3,1) = 1/4; a(3,2) = 1/4; b = [1/6, 1/6, 2/3]; c = [0 1 1/2]; case 4 % Standard RK4 s = 4; a = zeros(s,s-1); a(2,1) = 1/2; a(3,1) = 0; a(3,2) = 1/2; a(4,1) = 0; a(4,2) = 0; a(4,3) = 1; b = [1/6 1/3 1/3 1/6]; c = [0, 1/2, 1/2, 1]; % case 4-3/8 % % 3/8 RK4 (Kuttas method). Lower truncation error, more flops % s = 4; % a = zeros(s,s-1); % a(2,1) = 1/3; % a(3,1) = -1/3; a(3,2) = 1; % a(4,1) = 1; a(4,2) = -1; a(4,3) = 1; % b = [1/8 3/8 3/8 1/8]; % c = [0, 1/3, 2/3, 1]; case 6 % Runge-Kutta 6 from Alshina07 s = 7; a = zeros(s,s-1); a(2,1) = 4/7; a(3,1) = 115/112; a(3,2) = -5/16; a(4,1) = 589/630; a(4,2) = 5/18; a(4,3) = -16/45; a(5,1) = 229/1200 - 29/6000*sqrt(5); a(5,2) = 119/240 - 187/1200*sqrt(5); a(5,3) = -14/75 + 34/375*sqrt(5); a(5,4) = -3/100*sqrt(5); a(6,1) = 71/2400 - 587/12000*sqrt(5); a(6,2) = 187/480 - 391/2400*sqrt(5); a(6,3) = -38/75 + 26/375*sqrt(5); a(6,4) = 27/80 - 3/400*sqrt(5); a(6,5) = (1+sqrt(5))/4; a(7,1) = -49/480 + 43/160*sqrt(5); a(7,2) = -425/96 + 51/32*sqrt(5); a(7,3) = 52/15 - 4/5*sqrt(5); a(7,4) = -27/16 + 3/16*sqrt(5); a(7,5) = 5/4 - 3/4*sqrt(5); a(7,6) = 5/2 - 1/2*sqrt(5); b = [1/12 0 0 0 5/12 5/12 1/12]; c = [0, 4/7, 5/7, 6/7, (5-sqrt(5))/10, (5+sqrt(5))/10, 1]; otherwise error('That Runge-Kutta order is not implemented', order) end