# Error "List encountered within..." in DSolve[ ]?

Posted 21 days ago
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 c=3*10^8 T=0 h=1.0545718* 10^(-34) u={1,0,0,T}/Norm[{1,0,0,T}] v={0,1,0,T}/Norm[{0,1,0,T}] a={0,1,0,T} ⋅{0,0,c,T} b={0,0,1,T} ⋅{0,c,0,T} d= {0,0,1,T} ⋅{c,0,0,T} pde =I*h^2*(u⋅a-u⋅b)*D[psi[x, y,z,t],x] -I*h^2*(u⋅a)*D[psi[x, y,z,t],y]+ I*h^2*(u⋅b)* D[psi[x, y,z,t],z]-I*h^2*(v⋅d)*D[psi[x, y,z,t],z]+ I*h^2*(v⋅d)*(D[psi[x, y,z,t],y]) == 0 Then I try to solve it: DSolve[pde,{psiT[x,y,z,t],psiX[x,y,z,t],psiY[x,y,z,t],psiZ[x,y,z,t],psiT[x,y,z,t],psiX[x,y,z,t],psiY[x,y,z,t],psiZ[x,y,z,t]},{t,x,y,z}] But get the message:"List encountered within <<1>>==0. there should be no list on either side"..What is the cause of this, and how should I write it correctly?Thanks Answer
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Posted 21 days ago
 Probably the result of preexisting values for some symbols. Try clearing all symbols in the current context and reevaluating the code. ClearAll[Evaluate[Context[] <> "*"]] Answer
Posted 21 days ago
 Hi Rohit, I found some inconsistencies with cdot and asterisk symbols, after correcting these, I get a working code, but a new and quite different problem: c=3*10^8 T=2 h=1.0545718* 10^(-34) u={1,0,0,T}/Norm[{1,0,0,T}] v={0,1,0,T}/Norm[{0,1,0,T}] a={0,1,0,T}*{0,0,c,T} b={0,0,1,T} *{0,c,0,T} d= {0,0,1,T} *{c,0,0,T} pde =I*h^2*(u*a-u*b)*D[psi[x, y,z,t],x] - I*h^2*(u*a)*D[psi[x, y,z,t],y]+I*h^2*(u*b)* D[psi[x, y,z,t],z]- I*h^2*(v*d)*D[psi[x, y,z,t],z]+I*h^2*(v*d)*(D[psi[x, y,z,t],y]) == 0 Then when solving it: dsol=DSolve[pde,{psiT[x,y,z,t],psiX[x,y,z,t],psiY[x,y,z,t],psiZ[x,y,z,t],psiT[x,y,z,t],psiX[x,y,z,t],psiY[x,y,z,t],psiZ[x,y,z,t]},{t,x,y,z}];  Supplied equations are not differential or integral equations of the given functions. This happens no matter what values the vectors attain.This should not be the case, if the vectors don't cancel out. Answer
Posted 21 days ago
 Evaluate the variable pde. You will see the source of the problem.  Answer
Posted 21 days ago
 As written in the discussion, this problem is there what ever the coefficients are. In your case they give 0=0. If you change them, they don't give this equality, and still it doesn't solve. Try this: c=3*10^8 T=2 h=1.0545718* 10^(-34) u={1,0,0,T}/Norm[{1,0,0,T}] v={0,1,0,T}/Norm[{0,1,0,T}] a={0,1,0,T}*{0,0,c,T} b={1,1,1,T} *{c,c,c,T} d= {1,0,1,T} *{c,c,c,T} pde =I*h^2*(u*a-u*b)*D[psi[x, y,z,t],x] - I*h^2*(u*a)*D[psi[x, y,z,t],y]+ I*h^2*(u*b)* D[psi[x, y,z,t],z]-I*h^2*(v*d)*D[psi[x, y,z,t],z]+ I*h^2*(v*d)*(D[psi[x, y,z,t],y]) == 0 dsol=DSolve[pde,{psiT[x,y,z,t],psiX[x,y,z,t],psiY[x,y,z,t],psiZ[x,y,z,t], psiT[x,y,z,t],psiX[x,y,z,t],psiY[x,y,z,t],psiZ[x,y,z,t]},{t,x,y,z}];  DSolve", "deqx", "\"Supplied equations are not differential or integral equations of the given functions.\ So this 0=0 is not the problem. Something else is. Answer