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view +time/+rk/get_rk4_time_step.m @ 1031:2ef20d00b386 feature/advectionRV

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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 c6fcee3fcf1b
children 1a265a376b36
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% Calculate the size of the largest time step given the largest evalue for a operator with pure imaginary e.values.
function k = get_rk4_time_step(lambda,l_type)
    default_arg('l_type','complex')

    rad = abs(lambda);
    if strcmp(l_type,'real')
        % Real eigenvalue
        % kl > -2.7852
        k = 2.7852/rad;

    elseif strcmp(l_type,'imag')
        % Imaginary eigenvalue
        % |kl| < 2.8284
        k = 2.8284/rad;
    elseif strcmp(l_type,'complex')
        % |kl| < 2.5
        k = 2.5/rad;
    else
        error('l_type must be one of ''real'',''imag'' or ''complex''.')
    end
end