Why am I getting this error?

*To*: mathgroup at smc.vnet.net*Subject*: [mg60341] Why am I getting this error?*From*: ksmath <kdsimon at uiuc.edu>*Date*: Tue, 13 Sep 2005 06:07:51 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

I am attempting to solve a system with 3 pde's and I keep getting this error even though I think all of my equations have independent variables: NDSolve::dvnoarg: The function v appears with no arguments. If anyone could find the mistake in my code I would really appreciate it. C,V, and R are the dependent variables, and t (time) and x(distance-does not depend on time) are the independent variables. All other variables are constants. Thank you for any assistance you can provide me. \!\(\(rRHS\ = \ \(d\_r\) D[r[t, x], {x, 2}] + Î² \((1 - \((r[t, x] - r\_base)\)/\((k\_r - r\_base)\))\) \((r[t, x] - r\_base)\);\)\[IndentingNewLine] \(vRHS\ = \ \(d\_v\) D[v[t, x], {x, 2}] - Ï?\ v[t, x]\ - Î·\ v[t, x]\ c[t, x]/\((Î³\_1 + v[t, x])\) + If[ q\_large < q\_min, Î» \((q\_large - q\_min)\), 0];\)\[IndentingNewLine] \(\(cRHS\ = \ D[c[t, x]\ v[t, x]\ D[v[t, x], x], x] + If[v[ t, x] â?¥ v\_g, Ï?\ v[t, x]\ c[t, x]\ /\((Î³\_2 + v[t, x])\), Ï? \((v[t, x] - v\_d)\) c[t, x]];\)\(\[IndentingNewLine]\) \)\[IndentingNewLine] \(reqn\ = D[r[t, x], t]\ == \ rRHS;\)\[IndentingNewLine] \(veqn\ = \ D[v[t, x], t]\ == \ vRHS;\)\[IndentingNewLine] \(ceqn\ = \ D[c[t, x], t]\ == \ cRHS;\)\) BC1 = Derivative[0, 1][r][t, 0] == 0; BC2 = Derivative[0, 1][r][t, 1] == 0; BC3 = Derivative[0, 1][v][t, 0] == 0; BC4 = Derivative[0, 1][v][t, 1] == 0; BC5 = c[t, 0] == 1; BC6 = c[t, 1] v[t, 1] Derivative[0, 1][v][t, 1] == 0; \!\(\(c\_init = \(c\_o\) Exp \((\(-150\) x\^2)\) == c[0, x];\)\[IndentingNewLine] \(r\_init = \((K\_r - r\_base)\) Exp \((\(-100\) x\^2)\) + r\_base == r[0, x];\)\ \[IndentingNewLine] \(v\_init = \((v\_g - v\_d)\)/\((2 v\_o)\) == v[0, x];\)\) \!\(\(solution\ = \ NDSolve[{reqn, \ veqn, \ ceqn, q1\_i, q2\_i, \ c\_init, \ v\_init, \ r\_init, \ BC1, \ BC2, \ BC3, \ BC4, \ BC5, \ BC6}, {r[t, x], v[t, x], c[t, x], q1[t, x], q2[t, x]}, {t, 0, 1}, {x, 0, 1}];\)\) Any help is much appreciated. Katie