ndsolve of coupled equation

• To: mathgroup at smc.vnet.net
• Subject: [mg116471] ndsolve of coupled equation
• From: tarun dutta <tarunduttaz at gmail.com>
• Date: Wed, 16 Feb 2011 04:36:55 -0500 (EST)

```n = 5;
p = 5/1000;
q = 1/10;
c[i_][t] = a[i][t];
d[i_][t] = b[i][t];

eqn = Join[
Table[{c[i]'[t] == ((1/2)*i (i - 1) - q*i)*c[i][t] -
p*(Sqrt[i]*
c[i - 1][t]*(Sum[Sqrt[i]*d[i - 1][t]*d[i][t], {i, 0, n}]) +
Sqrt[i + 1]*
c[i + 1][
t]*(Sum[Sqrt[i + 1]*d[i - 1][t]*d[i][t], {i, 0, n}])),
d[i]'[t] == ((1/2)*i (i - 1) - q*i)*d[i][t] -
p*(Sqrt[i]*
d[i - 1][t]*(Sum[Sqrt[i]*c[i - 1][t]*c[i][t], {i, 0, n}]) +
Sqrt[i + 1]*
d[i + 1][
t]*(Sum[
Sqrt[i + 1]*c[i - 1][t]*c[i][t], {i, 0, n}]))}, {i, 0,
n}], Sum[(c[i]^2)[t], {i, 0, n}] == 1,
Sum[(d[i]^2)[t], {i, 0, n}] ==
1, {c[0][0] == 0.004567 == d[0][0]}, {Table[
c[i][0] == 0.0000000034, {i, 1, 5}],
Table[d[i][0] == 0.0000000034, {i, 1, 5}]}];
vars1 = Table[c[i][t], {i, 0, 5}];
vars2 = Table[d[i][t], {i, 0, 5}];
vars = Join[vars1, vars2];
sol = NDSolve[eqn, vars, {t, 1/10}]

it shows some error as NDSolve::deqn..
give some explanation..
regards,
tarun

```

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