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annotate +time/+rk4/get_rk4_time_step.m @ 86:3c39dd714fb6

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In Curve: Added numerical FD differentiation if derivative is not supplied. Added arc length computation based on the derivative. Added arc length parameterization (but this function is very slow.). In +util: Added fzero_vec.m and integral_vec.m, which call fzero and integral but take vector arguments.
author Martin Almquist <martin.almquist@it.uu.se>
date Sun, 29 Nov 2015 14:28:53 +0100
parents 48b6fb693025
children
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Jonatan Werpers <jonatan@werpers.com>
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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