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annotate +time/+rk/get_rk4_time_step.m @ 1012:1e437c9e5132 feature/advectionRV

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Create residual viscosity package +rv and generalize the ResidualViscosity class - Generalize residual viscosity, by passing user-defined flux and calculating the time derivative outside of the update. - Create separate RungekuttaRV specifically using interior RV updates - Separate the artifical dissipation operator from the scheme AdvectionRV1D so that the same scheme can be reused for creating the diff op used by the ResidualViscosity class
author Vidar Stiernström <vidar.stiernstrom@it.uu.se>
date Wed, 05 Dec 2018 13:44:10 +0100
parents c6fcee3fcf1b
children 1a265a376b36
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1 % Calculate the size of the largest time step given the largest evalue for a operator with pure imaginary e.values.
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2 function k = get_rk4_time_step(lambda,l_type)
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3 default_arg('l_type','complex')
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4
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5 rad = abs(lambda);
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6 if strcmp(l_type,'real')
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7 % Real eigenvalue
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8 % kl > -2.7852
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9 k = 2.7852/rad;
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10
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11 elseif strcmp(l_type,'imag')
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12 % Imaginary eigenvalue
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13 % |kl| < 2.8284
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14 k = 2.8284/rad;
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15 elseif strcmp(l_type,'complex')
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16 % |kl| < 2.5
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17 k = 2.5/rad;
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18 else
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19 error('l_type must be one of ''real'',''imag'' or ''complex''.')
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20 end
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21 end