annotate +time/+cdiff/cdiff.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> |
| date |
Thu, 17 Jan 2019 10:25:06 +0100 |
| parents |
48b6fb693025 |
| children |
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| rev |
line source |
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1 % Takes a step of
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2 % v_tt = Dv+Ev_t+S
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3 %
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4 % 1/k^2 * (v_next - 2v + v_prev) = Dv + E 1/(2k)(v_next - v_prev) + S
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5 %
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6 function [v_next, v] = cdiff(v, v_prev, k, D, E, S)
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7 % 1/k^2 * (v_next - 2v + v_prev) = Dv + E 1/(2k)(v_next - v_prev) + S
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8 % ekv to
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9 % A v_next = B v + C v_prev + S
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10 I = speye(size(D));
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11 A = 1/k^2 * I - 1/(2*k)*E;
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12 B = 2/k^2 * I + D;
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13 C = -1/k^2 * I - 1/(2*k)*E;
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14
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15 v_next = A\(B*v + C*v_prev + S);
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16 end |
