Mercurial > repos > public > sbplib
annotate +sbp/+implementations/d4_lonely_6_2.m @ 1198:2924b3a9b921 feature/d2_compatible
Add OpSet for fully compatible D2Variable, created from regular D2Variable by replacing d1 by first row of D1. Formal reduction by one order of accuracy at the boundary point.
author | Martin Almquist <malmquist@stanford.edu> |
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date | Fri, 16 Aug 2019 14:30:28 -0700 |
parents | b19e142fcae1 |
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rev | line source |
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324
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Created new operator class for lonely D4 operators. Removed some output parameters of implementations.
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1 function [H, HI, D4, e_l, e_r, M4, d2_l, d2_r, d3_l, d3_r, d1_l, d1_r] = d4_variable_6_2(m,h) |
312 | 2 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
3 %%% 6:te ordn. SBP Finita differens %%% | |
4 %%% operatorer med diagonal norm %%% | |
5 %%% Extension to variable koeff %%% | |
6 %%% %%% | |
7 %%% H (Normen) %%% | |
8 %%% D1=H^(-1)Q (approx f?rsta derivatan) %%% | |
9 %%% D2 (approx andra derivatan) %%% | |
10 %%% D2=HI*(R+C*D*S %%% | |
11 %%% %%% | |
12 %%% R=-D1'*H*C*D1-RR %%% | |
13 %%% %%% | |
14 %%% RR ?r dissipation) %%% | |
15 %%% Dissipationen uppbyggd av D4: %%% | |
16 %%% DI=D4*B*H*D4 %%% | |
17 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% | |
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18 |
312 | 19 % H?r med 6 RP ist?llet f?r 8 f?r D4 operatorn, dock samma randderivator |
20 % Denna ?r noggrannare, och har 2a ordningens randdslutning och b?r ge 6te | |
21 % ordningens konvergens. Hade dock ingen fri parameter att optimera | |
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22 |
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23 BP = 6; |
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24 if(m<2*BP) |
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25 error(['Operator requires at least ' num2str(2*BP) ' grid points']); |
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26 end |
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27 |
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28 % Norm |
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29 Hv = ones(m,1); |
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30 Hv(1:6) = [0.181e3/0.576e3, 0.1343e4/0.960e3, 0.293e3/0.480e3, 0.1811e4/0.1440e4, 0.289e3/0.320e3, 0.65e2/0.64e2]; |
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31 Hv(m-5:m) = rot90(Hv(1:6),2); |
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32 Hv = h*Hv; |
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33 H = spdiag(Hv, 0); |
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34 HI = spdiag(1./Hv, 0); |
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35 |
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36 |
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37 % Boundary operators |
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38 e_l = sparse(m,1); |
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39 e_l(1) = 1; |
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40 e_r = rot90(e_l, 2); |
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41 |
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42 d1_l = sparse(m,1); |
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43 d1_l(1:6) = [-0.137e3/0.60e2 5 -5 0.10e2/0.3e1 -0.5e1/0.4e1 0.1e1/0.5e1;]/h; |
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44 d1_r = -rot90(d1_l, 2); |
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45 |
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46 d2_l = sparse(m,1); |
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47 d2_l(1:6) = [0.15e2/0.4e1 -0.77e2/0.6e1 0.107e3/0.6e1 -13 0.61e2/0.12e2 -0.5e1/0.6e1;]/h^2; |
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48 d2_r = rot90(d2_l, 2); |
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49 |
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50 d3_l = sparse(m,1); |
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51 d3_l(1:6) = [-0.17e2/0.4e1 0.71e2/0.4e1 -0.59e2/0.2e1 0.49e2/0.2e1 -0.41e2/0.4e1 0.7e1/0.4e1;]/h^3; |
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52 d3_r = -rot90(d3_l, 2); |
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53 |
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54 |
312 | 55 % Fourth derivative, 1th order accurate at first 8 boundary points (still |
56 % yield 5th order convergence if stable: for example u_tt = -u_xxxx | |
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57 stencil = [7/240, -2/5, 169/60, -122/15, 91/8, -122/15, 169/60, -2/5, 7/240]; |
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58 diags = -4:4; |
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59 M4 = stripeMatrix(stencil, diags, m); |
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60 |
312 | 61 M4_U = [ |
62 0.1009e4/0.192e3 -0.7657e4/0.480e3 0.9307e4/0.480e3 -0.509e3/0.40e2 0.4621e4/0.960e3 -0.25e2/0.32e2; | |
63 -0.7657e4/0.480e3 0.49513e5/0.960e3 -0.4007e4/0.60e2 0.21799e5/0.480e3 -0.8171e4/0.480e3 0.2657e4/0.960e3; | |
64 0.9307e4/0.480e3 -0.4007e4/0.60e2 0.1399e4/0.15e2 -0.2721e4/0.40e2 0.12703e5/0.480e3 -0.521e3/0.120e3; | |
65 -0.509e3/0.40e2 0.21799e5/0.480e3 -0.2721e4/0.40e2 0.3349e4/0.60e2 -0.389e3/0.15e2 0.559e3/0.96e2; | |
66 0.4621e4/0.960e3 -0.8171e4/0.480e3 0.12703e5/0.480e3 -0.389e3/0.15e2 0.17857e5/0.960e3 -0.1499e4/0.160e3; | |
67 -0.25e2/0.32e2 0.2657e4/0.960e3 -0.521e3/0.120e3 0.559e3/0.96e2 -0.1499e4/0.160e3 0.2225e4/0.192e3; | |
68 ]; | |
69 | |
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70 |
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71 M4(1:6,1:6) = M4_U; |
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72 M4(m-5:m,m-5:m) = rot90(M4_U, 2); |
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73 M4 = 1/h^3*M4; |
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74 |
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75 D4=HI*(M4 - e_l*d3_l'+e_r*d3_r' + d1_l*d2_l'-d1_r*d2_r'); |
312 | 76 end |