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view +sbp/+implementations/d2_variable_2.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 | 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