Question: Solving a system of pdes

I am trying to solve these equations but I dont know how...

> sys := [diff(v(s, n), n)+diff(u(s, n), s)+diff(xi(s, n), s)+A*n*(diff(c(s), s)) = 0, A1*(diff(xi(s, n), n))+diff(v(s, n), s)-c(s)+A2*v(s, n)+A3*c(s) = 0, diff(u(s, n), s)+2*A2*u(s, n) = A2*(xi(s, n)+A*n*c(s))-A1*(diff(xi(s, n), s))-A2*n*c(s)];

 

print(`output redirected...`); # input placeholder

 

[/ d         \   / d         \   / d          \       / d      \      

 

[|--- v(s, n)| + |--- u(s, n)| + |--- xi(s, n)| + A n |--- c(s)| = 0,

 

[\ dn        /   \ ds        /   \ ds         /       \ ds     /      

 

     / d          \   / d         \                                    / d    

 

  A1 |--- xi(s, n)| + |--- v(s, n)| - c(s) + A2 v(s, n) + A3 c(s) = 0, |--- u(

 

     \ dn         /   \ ds        /                                    \ ds   

 

       \                                                / d          \

 

  s, n)| + 2 A2 u(s, n) = A2 (xi(s, n) + A n c(s)) - A1 |--- xi(s, n)|

 

       /                                                \ ds         /

 

              ]

 

   - A2 n c(s)]

 

              ]

 

> sys;

 

print(`output redirected...`); # input placeholder

 

[/ d         \   / d         \   / d          \       / d      \      

 

[|--- v(s, n)| + |--- u(s, n)| + |--- xi(s, n)| + A n |--- c(s)| = 0,

 

[\ dn        /   \ ds        /   \ ds         /       \ ds     /      

 

     / d          \   / d         \                                    / d    

 

  A1 |--- xi(s, n)| + |--- v(s, n)| - c(s) + A2 v(s, n) + A3 c(s) = 0, |--- u(

 

     \ dn         /   \ ds        /                                    \ ds   

 

       \                                                / d          \

 

  s, n)| + 2 A2 u(s, n) = A2 (xi(s, n) + A n c(s)) - A1 |--- xi(s, n)|

 

       /                                                \ ds         /

 

              ]

 

   - A2 n c(s)]

 

              ]

 

> bc := {v(s, -1) = 0, v(s, 1) = 0};

 

print(`output redirected...`); # input placeholder

 

                         {v(s, -1) = 0, v(s, 1) = 0}

 

> ans := pdsolve(sys, bc);

 

%;

 

Error, (in pdsolve/sys/info) required an indication of the dependent variables in the given system

 

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