class_docstr: Simple zeroth-order activation dynamics mapping excitation to
  activation.
  
  Explanation
  ===========
  
  Zeroth-order activation dynamics are useful in instances where you want to
  reduce the complexity of your musculotendon dynamics as they simple map
  exictation to activation. As a result, no additional state equations are
  introduced to your system. They also remove a potential source of delay
  between the input and dynamics of your system as no (ordinary) differential
  equations are involed.
class_docstr_tok: ["Simple","zeroth-order","activation","dynamics","mapping","excitation","to","activation",".","Explanation","===========","Zeroth-order","activation","dynamics","are","useful","in","instances","where","you","want","to","reduce","the","complexity","of","your","musculotendon","dynamics","as","they","simple","map","exictation","to","activation",".","As","a","result",",","no","additional","state","equations","are","introduced","to","your","system",".","They","also","remove","a","potential","source","of","delay","between","the","input","and","dynamics","of","your","system","as","no","(","ordinary",")","differential","equations","are","involed","."]
docstr: Ordered column matrix of equations for the solution of ``M x' = F``.
  
  Explanation
  ===========
  
  The solution to the linear system of ordinary differential equations
  governing the activation dynamics:
  
  ``M(x, r, t, p) x' = F(x, r, t, p)``.
  
  As zeroth-order activation dynamics have no state variables, this
  linear has dimension 0 and therefore this method returns an empty
  column ``Matrix`` with shape (0, 1).
docstr_tok: ["Ordered","column","matrix","of","equations","for","the","solution","of","``","M","x","'","=","F","``",".","Explanation","===========","The","solution","to","the","linear","system","of","ordinary","differential","equations","governing","the","activation","dynamics",":","``","M","(","x",",","r",",","t",",","p",")","x","'","=","F","(","x",",","r",",","t",",","p",")","``",".","As","zeroth-order","activation","dynamics","have","no","state","variables",",","this","linear","has","dimension","0","and","therefore","this","method","returns","an","empty","column","``","Matrix","``","with","shape","(","0",",","1",")","."]
code: def rhs(self):
      """Ordered column matrix of equations for the solution of ``M x' = F``.
  
      Explanation
      ===========
  
      The solution to the linear system of ordinary differential equations
      governing the activation dynamics:
  
      ``M(x, r, t, p) x' = F(x, r, t, p)``.
  
      As zeroth-order activation dynamics have no state variables, this
      linear has dimension 0 and therefore this method returns an empty
      column ``Matrix`` with shape (0, 1).
  
      """
      return zeros(0, 1)
  
imports: from abc import ABC, abstractmethod
  from functools import cached_property
  from sympy.core.symbol import Symbol
  from sympy.core.numbers import Float, Integer, Rational
  from sympy.functions.elementary.hyperbolic import tanh
  from sympy.matrices.dense import MutableDenseMatrix, zeros
  from sympy.physics.biomechanics._mixin import _NamedMixin
  from sympy.physics.mechanics import dynamicsymbols
label_desc: Use image node_id 12 for calling the ZerothOrderActivation obj's underlying member method code with example usage: obj.rhs() and returns: zeros