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view +sbp/+implementations/d2_variable_2.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 | ded4156e53e2 |
children | b758d1cf4c8e |
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function [H, HI, D1, D2, e_l, e_r, d1_l, d1_r] = d2_variable_2(m,h) BP = 1; if(m<2*BP) error(['Operator requires at least ' num2str(2*BP) ' grid points']); end % Norm Hv = ones(m,1); Hv(1) = 1/2; Hv(m:m) = 1/2; Hv = h*Hv; H = spdiag(Hv, 0); HI = spdiag(1./Hv, 0); % Boundary operators e_l = sparse(m,1); e_l(1) = 1; e_r = rot90(e_l, 2); d1_l = sparse(m,1); d1_l(1:3) = 1/h*[-3/2 2 -1/2]; d1_r = -rot90(d1_l, 2); % D1 operator diags = -1:1; stencil = [-1/2 0 1/2]; D1 = stripeMatrix(stencil, diags, m); D1(1,1)=-1;D1(1,2)=1;D1(m,m-1)=-1;D1(m,m)=1; D1(m,m-1)=-1;D1(m,m)=1; D1=D1/h; %Q=H*D1 + 1/2*(e_1*e_1') - 1/2*(e_m*e_m'); M=sparse(m,m); scheme_width = 3; scheme_radius = (scheme_width-1)/2; r = (1+scheme_radius):(m-scheme_radius); function D2 = D2_fun(c) Mm1 = -c(r-1)/2 - c(r)/2; M0 = c(r-1)/2 + c(r) + c(r+1)/2; Mp1 = -c(r)/2 - c(r+1)/2; M(r,:) = spdiags([Mm1 M0 Mp1],0:2*scheme_radius,length(r),m); M(1:2,1:2)=[c(1)/2 + c(2)/2 -c(1)/2 - c(2)/2; -c(1)/2 - c(2)/2 c(1)/2 + c(2) + c(3)/2;]; M(m-1:m,m-1:m)=[c(m-2)/2 + c(m-1) + c(m)/2 -c(m-1)/2 - c(m)/2; -c(m-1)/2 - c(m)/2 c(m-1)/2 + c(m)/2;]; M=M/h; D2=HI*(-M-c(1)*e_l*d1_l'+c(m)*e_r*d1_r'); end D2 = @D2_fun; end