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## pydstool-users

 [pydstool-users] Matrix in system of equation From: Achim Ammon - 2011-01-12 06:29:19 Attachments: Message as HTML Hi Happy new year every one! I'm new to continuation and trying to get my head around things at the moment. I've got the following system of equation: $$\left( \begin{array}{c} \dot{s}\\ \dot{v} \end{array} \right) = \left( \begin{array}{c} v\\ -\mathbf{B}^{-1} \mathbf{A} s + V_{DC} \mathbf{B}^{-1} \mathbf{C} s \end{array} \right)$$ where A B and C are square matrices of dimension (nxn), s and v are vectors of length n and V_DC is a scalar. I tried to enter this system of equations and solve it with pyDSTool but got; 'TypeError: only length-1 arrays can be converted to Python scalars'. Here's the code: > #!/usr/bin/python > # encoding=utf8 > > import PyDSTool as DS > import numpy as np > > AA = np.matrix([[127.717469865, 2.05025780562], > [0.0521863096197, 2605.29996274]]) > BB = np.matrix([[1.65676839951e-10, 6.76971107431e-14], > [6.76971107431e-14, 8.60513163289e-11]]) > CC = np.matrix([[-5.91089367427436, 58.2428565496970], > [-9.30459729674465, 47.6048481884652]]) > > > DSargs = DS.args(name='Hopf') > > # parameters > DSargs.pars = { > 'A': AA, > 'B': BB, > 'B_I': BB.I, > 'C': CC, > 'V_DC': 0 > } > > # auxiliary helper function(s) > DSargs.fnspecs = { > 'ss': (['s'], 'sum(s)'), > 'vv': (['v'], 'sum(v)') > } > > # rhs of the differential equation > DSargs.varspecs = { > 's': 'v', > 'v': '-B_I*A*s + V_DC*B_I*C*s' > } > > # initial conditions > DSargs.ics = { > 's': np.matrix([0,0]), > 'v': np.matrix([0,0]) > } > > DSargs.info() > > ode = DS.Generator.Vode_ODEsystem(DSargs) > > # Set up continuation class > PyCont = DS.ContClass(ode) > > PCargs = DS.args(name='EQ1', type='EP-C') > PCargs.freepars = ['V_DC'] > PCargs.MaxNumPoints = 400 > PCargs.StepSize = 0.1 > PCargs.LocBifPoints = ['all'] > PCargs.SaveEigen = True > How can I deal with matrices in the system of equations? I need to work with such systems often in future as this is the form I get after applying the Galerking decomposition to continuum-mechanical dynamic systesm. Thanks for your help! Achim ps: Thanks for another awesome open-source tool!