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1 | 1 | classdef AscherLinearDAEProblem < otp.Problem |
2 | 2 | % A linear differential-algebraic problem with time-dependant mass matrix. |
3 | 3 | % |
4 | | - % The Ascher linear DAE Problem :cite:p:`Asc89` is an index-1 differential-agebraic |
5 | | - % equation given by |
| 4 | + % The Ascher linear DAE Problem :cite:p:`Asc89` is an index-1 differential-agebraic equation given by |
6 | 5 | % |
7 | 6 | % $$ |
8 | 7 | % \begin{bmatrix} |
9 | 8 | % 1 & -t \\ |
10 | 9 | % 0 & 0 |
11 | 10 | % \end{bmatrix} \begin{bmatrix} y'(t) \\ z'(t) \end{bmatrix} = \left[ \begin{array}{cc} |
12 | 11 | % -1 & 1+t \\ |
13 | | - % \beta & -1-\beta t |
| 12 | + % β & -1-β t |
14 | 13 | % \end{array}\right] \begin{bmatrix} y(t) \\ z(t) \end{bmatrix} + \begin{bmatrix} |
15 | 14 | % 0 \\ |
16 | | - % \sin t |
| 15 | + % \sin(t) |
17 | 16 | % \end{bmatrix}. |
18 | 17 | % $$ |
19 | 18 | % |
20 | | - % When the initial condition $y(0) = 1 , z(0) = \beta$ is used, the problem has the following closed-form solution: |
| 19 | + % When the initial condition $y(0) = 1 , z(0) = β$ is used, the problem has the following closed-form solution: |
21 | 20 | % |
22 | 21 | % $$ |
23 | 22 | % \begin{bmatrix} y(t)\\ z(t) \end{bmatrix} = \begin{bmatrix} |
24 | | - % t \sin(t) + (1 + \beta t) e^{-t}\\ |
25 | | - % \beta e^{-t} + \sin(t) |
| 23 | + % t \sin(t) + (1 + β t) e^{-t}\\ |
| 24 | + % β e^{-t} + \sin(t) |
26 | 25 | % \end{bmatrix}. |
27 | 26 | % $$ |
28 | | - % This DAE problem |
29 | | - % can be used to investigate |
30 | | - % the convergence of implcit time-stepping methods due to its stiffness and time-dependant mass |
31 | | - % matrix. |
| 27 | + % This DAE problem can be used to investigate the convergence of implcit time-stepping methods due to its stiffness |
| 28 | + % and time-dependant mass matrix. |
32 | 29 | % |
33 | 30 | % Notes |
34 | 31 | % ----- |
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37 | 34 | % +---------------------+-----------------------------------------+ |
38 | 35 | % | Number of Variables | 2 | |
39 | 36 | % +---------------------+-----------------------------------------+ |
40 | | - % | Stiff | possibly, depending on $\beta$ | |
| 37 | + % | Stiff | possibly, depending on $β$ | |
41 | 38 | % +---------------------+-----------------------------------------+ |
42 | 39 | % |
43 | 40 | % Example |
44 | 41 | % ------- |
45 | 42 | % >>> problem = otp.ascherlineardae.presets.Canonical('Beta', 50); |
46 | | - % >>> t = linspace(0,1); |
| 43 | + % >>> t = linspace(0, 1); |
47 | 44 | % >>> sol = problem.solveExactly(t); |
48 | 45 | % >>> problem.plot(t, sol); |
49 | 46 |
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@@ -76,9 +73,9 @@ function onSettingsChanged(obj) |
76 | 73 |
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77 | 74 | function label = internalIndex2label(~, index) |
78 | 75 | if index == 1 |
79 | | - label = 'Differential Variable'; |
| 76 | + label = 'Differential'; |
80 | 77 | else |
81 | | - label = 'Algebraic Variable'; |
| 78 | + label = 'Algebraic'; |
82 | 79 | end |
83 | 80 | end |
84 | 81 |
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