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Mathematics Calculus Equation Solving Wolfram Language

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

Ser Man

Posted 4 years ago

c=310^8 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 =Ih^2(u⋅a-u⋅b)D[psi[x, y,z,t],x] -Ih^2(u⋅a)D[psi[x, y,z,t],y]+ Ih^2(u⋅b)* D[psi[x, y,z,t],z]-Ih^2(v⋅d)D[psi[x, y,z,t],z]+ Ih^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

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

POSTED BY: Ser Man

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Hans Milton

Posted 4 years ago

Evaluate the variable `pde`. You will see the source of the problem.

POSTED BY: Hans Milton

Ser Man

Posted 4 years 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=310^8 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 =Ih^2(ua-ub)D[psi[x, y,z,t],x] - Ih^2(ua)D[psi[x, y,z,t],y]+ Ih^2(ub) D[psi[x, y,z,t],z]-Ih^2(vd)D[psi[x, y,z,t],z]+ Ih^2(vd)(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.

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.

POSTED BY: Ser Man

Rohit Namjoshi

Posted 4 years 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[] <> "*"]]

POSTED BY: Rohit Namjoshi

Ser Man

Posted 4 years ago

POSTED BY: Ser Man

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