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view +time/+rk/butcherTableau.m @ 1031:2ef20d00b386 feature/advectionRV
For easier comparison, return both the first order and residual viscosity when evaluating the residual. Add the first order and residual viscosity to the state of the RungekuttaRV time steppers
author | Vidar Stiernström <vidar.stiernstrom@it.uu.se> |
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date | Thu, 17 Jan 2019 10:25:06 +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