Mercurial > repos > public > sbplib
diff diracDiscr.m @ 836:049e4c6fa630 feature/poroelastic
Add dirac delta function, with corresponding test. Commented out tests for staggered grid because they do not yet exist on this branch.
author | Martin Almquist <malmquist@stanford.edu> |
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date | Wed, 05 Sep 2018 14:46:39 -0700 |
parents | |
children | 43a1c3ac07b1 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/diracDiscr.m Wed Sep 05 14:46:39 2018 -0700 @@ -0,0 +1,97 @@ +function ret = diracDiscr(x_0in , x , m_order, s_order, H, h) + +m = length(x); + +% Return zeros if x0 is outside grid +if(x_0in < x(1) || x_0in > x(end) ) + + ret = zeros(size(x)); + +else + + fnorm = diag(H); + eta = abs(x-x_0in); + tot = m_order+s_order; + S = []; + M = []; + + % Get interior grid spacing + middle = floor(m/2); + h = x(middle+1) - x(middle); + + poss = find(tot*h/2 >= eta); + + % Ensure that poss is not too long + if length(poss) == (tot + 2) + poss = poss(2:end-1); + elseif length(poss) == (tot + 1) + poss = poss(1:end-1); + end + + % Use first tot grid points + if length(poss)<tot && x_0in < x(1) + ceil(tot/2)*h; + index=1:tot; + pol=(x(1:tot)-x(1))/(x(tot)-x(1)); + x_0=(x_0in-x(1))/(x(tot)-x(1)); + norm=fnorm(1:tot)/h; + + % Use last tot grid points + elseif length(poss)<tot && x_0in > x(end) - ceil(tot/2)*h; + index = length(x)-tot+1:length(x); + pol = (x(end-tot+1:end)-x(end-tot+1))/(x(end)-x(end-tot+1)); + norm = fnorm(end-tot+1:end)/h; + x_0 = (x_0in-x(end-tot+1))/(x(end)-x(end-tot+1)); + + % Interior, compensate for round-off errors. + elseif length(poss) < tot + if poss(end)<m + poss = [poss; poss(end)+1]; + else + poss = [poss(1)-1; poss]; + end + pol = (x(poss)-x(poss(1)))/(x(poss(end))-x(poss(1))); + x_0 = (x_0in-x(poss(1)))/(x(poss(end))-x(poss(1))); + norm = fnorm(poss)/h; + index = poss; + + % Interior + else + pol = (x(poss)-x(poss(1)))/(x(poss(end))-x(poss(1))); + x_0 = (x_0in-x(poss(1)))/(x(poss(end))-x(poss(1))); + norm = fnorm(poss)/h; + index = poss; + end + + h_pol = pol(2)-pol(1); + b = zeros(m_order+s_order,1); + + for i = 1:m_order + b(i,1) = x_0^(i-1); + end + + for i = 1:(m_order+s_order) + for j = 1:m_order + M(j,i) = pol(i)^(j-1)*h_pol*norm(i); + end + end + + for i = 1:(m_order+s_order) + for j = 1:s_order + S(j,i) = (-1)^(i-1)*pol(i)^(j-1); + end + end + + A = [M;S]; + + d = A\b; + ret = x*0; + ret(index) = d/h*h_pol; +end + +end + + + + + +