NDSolve Singularity
- To: mathgroup at smc.vnet.net
- Subject: [mg85504] NDSolve Singularity
- From: Tara.Ann.Lorenz at gmail.com
- Date: Wed, 13 Feb 2008 04:08:04 -0500 (EST)
Hello,
The following input for NDSolve is giving me a "singularity" error
(see error message below). As a result, my system of equations is
being solved until the singularity at t=0.179 and not until t=30 as
desired. Any suggestions on how to avoid this issue? Thank you!
va = 4.71*y[t] - 246;
q = 6;
kl = 5;
kt = 40;
b = 760;
mrco2 = 250;
caco2 = 48 + 6*(paco2 - 40)/7;
paco2 = (b - 47)*r[t];
fico2 = 0.07;
grodinstime0to30 =
NDSolve[{r'[
t] == (1/
kl)*((fico2*va + 8.63*q*(y[t] - caco2)/(b - 47) - r[t]*va)),
y'[t] == (mrco2 + 10*q*(caco2 - y[t]))/(10*kt), r[0] == 0.058,
y[0] == 0.533}, {r, y}, {t, 0, 30}]
ERROR MESSAGE:
NDSolve::ndsz: At t == 0.17926445744166167`, step size is effectively
zero; singularity or stiff system suspected. >>