<?xml version="1.0" encoding="UTF-8"?> <simulation xmds-version="2"> <name>van_der_pol</name> <author>Graham Dennis</author> <description> Van der Pol oscillator. An example of a stiff equation. </description> <features> <benchmark /> <error_check /> <bing /> <!-- That's right, this script breaks the shackles with FFTW! --> <arguments> <argument name="lambda" type="real" default_value="100.0" /> <![CDATA[ _LOG(_SIMULATION_LOG_LEVEL, "lambda is %e\n", lambda); ]]> </arguments> </features> <geometry> <propagation_dimension> t </propagation_dimension> </geometry> <vector name="main" type="real"> <components> y yDot </components> <initialisation> <![CDATA[ y = 1.0; yDot = 0.0; ]]> </initialisation> </vector> <sequence> <integrate algorithm="ARK89" interval="100.0" steps="25000" tolerance="1e-7"> <samples>5000</samples> <operators> <integration_vectors>main</integration_vectors> <![CDATA[ dy_dt = yDot; dyDot_dt = lambda*(1.0 - y*y)*yDot - y; ]]> </operators> </integrate> </sequence> <output> <sampling_group initial_sample="yes"> <moments>yR yDotR</moments> <dependencies>main</dependencies> <![CDATA[ yR = y; yDotR = yDot; ]]> </sampling_group> </output> </simulation>