Mercurial > repos > public > sbplib
changeset 505:49bc2929dfb1 feature/quantumTriangles
Added the midpont magnus exponential integrator
author | Ylva Rydin <ylva.rydin@telia.com> |
---|---|
date | Thu, 18 May 2017 11:44:29 +0200 |
parents | 7fe1782d5224 |
children | 2047ff9640b3 |
files | +time/+expint/Magnus_mp.m +time/MagnusMP.m |
diffstat | 2 files changed, 57 insertions(+), 0 deletions(-) [+] |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/+time/+expint/Magnus_mp.m Thu May 18 11:44:29 2017 +0200 @@ -0,0 +1,14 @@ +% Takes one time step of size k using the magnus midpoinr +% starting from v_0 and where the function F(v,t) gives the +% time derivatives. +function v = Magnus_mp(v,D, t , k) + +if isa(D,'function_handle') + % v = krylov(k*D(t +k/2*t),v); + v = expm(k*D(t +k/2*t))*v; +else + %v = krylov(k*D,v); + v = expm(k*D)*v; +end + +end \ No newline at end of file
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/+time/MagnusMP.m Thu May 18 11:44:29 2017 +0200 @@ -0,0 +1,43 @@ +classdef MagnusMP < time.Timestepper + properties + D + S + F + k + t + v + m + n + end + + + methods + function obj = MagnusMP(D, k, t0, v0) + obj.D = D; + obj.k = k; + obj.t = t0; + obj.v = v0; + obj.m = length(v0); + obj.n = 0; + end + + function [v,t] = getV(obj) + v = obj.v; + t = obj.t; + end + + function obj = step(obj) + obj.v = time.expint.Magnus_mp(obj.v,obj.D, obj.t, obj.k); + obj.t = obj.t + obj.k; + obj.n = obj.n + 1; + end + end + + + methods (Static) + function k = getTimeStep(lambda) + k = rk4.get_rk4_time_step(lambda); + end + end + +end \ No newline at end of file