A problem with derivative InterpolatingFunction from NDSolve
- To: mathgroup at smc.vnet.net
- Subject: [mg94680] A problem with derivative InterpolatingFunction from NDSolve
- From: bar at ANTYSPAM.ap.krakow.pl
- Date: Sat, 20 Dec 2008 06:20:29 -0500 (EST)
When i use an iteration with a derivative InterpolatingFunction
Mathematica uses more than enough memory ( memory icreases in every steps)
This is the sample:
--------------
For[jj = 0, jj < 2,
alf = N[1 - jj/20];
Print["alf= ", alf];
dj = 1/200;
For[j = 0, j < 3,
ni = N[1.2 + j dj];
start = 0;
tmax = 4000;
eq1 = u1''[t] + 5 alf u1[t] + ni u2[t] == 0;
eq2 = u2''[t] + 3 u2[t] == 0;
sol =
NDSolve[{eq1, eq2, u1[0] == 1, u1'[0] == 0, u2[0] == 1,
u2'[0] == 0}, {u1, u2}, {t, 0, tmax}, MaxSteps -> Infinity];
U1[t_] := Evaluate[u1[t] /. sol][[1]];
U2[t_] := Evaluate[u2[t] /. sol][[1]];
F[t_] := U1[t] + U2[t];
(*POINCARE ** ** ** ** **********)
lista = {};
start = 1500.;
T = 2 Pi/ni;
nt = 400;
AppendTo[lista, {U1[100], U1'[100]}];
Print[jj, j, " ", MemoryInUse[]];
j++];
jj++]
---------------------
When I try U1[t] in place of U1'[t]
everything's ok (MemoryInUse gives the same
in all steps)
Clear[u1,u2,U1,U2] doesn't help.
Any suggestions ?
Regards, Olaf