20 lines
No EOL
811 B
Matlab
20 lines
No EOL
811 B
Matlab
% assembling of the stiffness matrix and the load vector for a given mesh
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% in 1D
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function [K,f_vec] = assembling(nodes,lambda,f)
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n_nodes = length(nodes);
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K = zeros(n_nodes);
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f_vec = zeros(n_nodes,1);
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h_diff_vec = nodes(2:end) - nodes(1:end-1); % step width
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for k = 1:n_nodes-1
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% stiffness matrix
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lambda_int = integral(lambda, nodes(k), nodes(k+1));
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K_loc = lambda_int/h_diff_vec(k)^2*[1,-1;-1,1];
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K(k:k+1,k:k+1) = K(k:k+1,k:k+1) + K_loc;
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% right hand side
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phi_left = @(x) (nodes(k+1)-x)/h_diff_vec(k).*f(x);
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phi_right = @(x) (x-nodes(k))/h_diff_vec(k).*f(x);
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f_loc = [integral(phi_left,nodes(k),nodes(k+1)); integral(phi_right,nodes(k),nodes(k+1))];
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f_vec(k:k+1) = f_vec(k:k+1) + f_loc;
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end
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end |