Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2011

[Date Index] [Thread Index] [Author Index]

Search the Archive

Question about adding events to ndsolve

  • To: mathgroup at smc.vnet.net
  • Subject: [mg120337] Question about adding events to ndsolve
  • From: Chrisantha Fernando <ctf20 at sussex.ac.uk>
  • Date: Tue, 19 Jul 2011 06:57:30 -0400 (EDT)

Please help with adding events to ndsolve. I need to change the 
concentrations discretely at certain points in time.

s = NDSolve[{Derivative[1][X0][t] == 0, Derivative[1][X1][t] == 
0,
   Derivative[1][X3][t] ==
    6.088416` X1[t] X4[t] - 0.000723` X3[t] X4[t] + 7.721115` X1[t] 
X7[t] -
     9.366268` X3[t] X8[t],
   Derivative[1][X4][t] == -30.` X0[t] X4[t] + 0.031364` X7[t] 
X8[t],
   Derivative[1][X7][t] ==
    30.` X0[t] X4[t] - 7.721115` X1[t] X7[t] + 9.366268` X3[t] X8[t] -

     0.031364` X7[t] X8[t],
   Derivative[1][X8][t] ==
    30.` X0[t] X4[t] + 7.721115` X1[t] X7[t] - 9.366268` X3[t] X8[t] -

     0.031364` X7[t] X8[t], X0[0] == 0.`, X1[0] == 0.`, X3[0] ==
 1,
   X4[0] == 1, X7[0] == 1, X8[0] == 1}, {X0, X1, X3, X4, X7, 
X8}, {t, 0, 30}]
Plot[Evaluate[{X1[x], X2[x],  X3[x],  X4[x],  X7[x],  X8[x]} /. s], {x, 
0,
  30}, PlotRange -> All]

and I'd like to add events such that at specific points in time I can 
change the values of the variables (chemicals) to a value that I set 
externally, i.e. these will be external stimuli to the ODEs that change 
the concentrations of chemicals discretely.

Cheers,
Chrisantha




  • Prev by Date: Re: Solve never calls Equal?
  • Next by Date: Re: numeric Groebner bases et al [Was Re: Numerical accuracy/precision - this is a bug or a feature?]
  • Previous by thread: Re: Generating Arbitrary Linear Combinations of Functions
  • Next by thread: Re: remarks on significance arithmetic implementation [Was: Re: Numerical accuracy/precision - this is a bug or a feature?]