I know you can filter a dataframe by putting constraints on the numeric columns. However, I would like to sort and filter based upon a given string in a column, is this possible? I cannot immediately find this in the help files. Thank you for your assistance.QuestionDataFrame.mw

Hi MaplePrimes. 

I have a cubic with some parameters that I would like to solve and recieve 3 real solutions, however I cannot seem to find a way to get that to work while using assumptions. I always recieve 1 real and two complex conjugate answers. I have tried assuming the discrimant to be greater then zero but nothing seems to be working, and I have looked through a few posts on here but I cant seem to find anything out. In particular solve({f,conditions},{variable}) 

If I solve with a known set of paramters(which i determine graphically) that gives three solutions everything works fine. Also if I solve the cubic generally and recieve the two complex solutions and one real then substitute the paramters in I get the same correct answers, so I am slightly baffled. If I have missed something simple my apologies. 

Any help would be greatly appreciated. File attached. 

CubicSolve.mw

HI, I have numerically solved the given problem using the dsolve command But I want to solve the same problem using the Differential transformation method.
Can anyone help me to get the series solution for the given problem using DTM.

I want to compare the numerical results with DTM results when lambda =0.5.

eqn1 := diff(f(eta), `$`(eta, 3))+f(eta)*(diff(f(eta), `$`(eta, 2)))-(diff(f(eta), eta))^2-lambda*(diff(f(eta), eta)) = 0.

eqn2 := diff(theta(eta), `$`(eta, 2))+f(eta)*(diff(theta(eta), eta))*Pr = 0

Bcs := (D(f))(0) = 1, f(0) = 0, (D(f))(infinity) = 0, theta(0) = 1, theta(infinity) = 0;

[lambda = .5, Pr = 6.3]

Evaluating this integral

produces an infinite product as output. Why does Maple not automatically simplify to infinity. Can the extra information (1+pi) be of any use?

Download Infinity_times_something.mw

Please how can I define two sequences in a procedure with two arguments?

  ans:= Array([seq( [j, doCalc(j, u)], j=-2..0, 0.006, u=1..334)]):

The procedure is doCalc(j,u)  and I received this error: invalid input: seq expects between 1 and 3 arguments, but received 4

Find attached my complete code.Seq_Proc.mw

Good Morning Guys,

Please, could somebody help me with my problem in Maple?

The expression y' = y^4 * cos(x) + y*tan(x) with start-value y(0) = 0.5 has the solution of 1/root(cos(x)^2 * 8*cos(x)-3 * sin(x),3).

If I try to solve it with this method dgl_2 := diff(y(x), x) = y(x)^4*cos(x) + y(x)*tan(x) I don't get the right solution. Is it possible to solve this expression with a Tutor app? step by step? If yes I would so happy to tell me how I can do that. 

Thanks a lot and I wish you all a nice sunday and stay safe.

Is there a way to importing cell values as text, and not numbers, when the cell is formatted as a text?

As far as I can see, a cell with the value "1" is always import as "1.0" in ExcelTools, regardless if the cell is formatted as text or something else in Excel.

Writing '1 in the Excel cell however leads to a text import in Maple, and will give "1", not "1.0".

There is one more thing that is strange in Excel. Even if the cell is formatted as a text, or the cell content is with a ' before the number, Excel will allow a calculation with that value. Text value 4 will give 5, if added 1.

Dear maple user how to rectify the error  in solving the coupled differential equation using homotropy perturbation method and direct differentiations and compare the two result by plotting the graphs :

restart:
with(PDEtools):
L:=4:Nb:=1:Nt:=1:#k is some constant
f(x):=sum((p^i)*f[i](x),i=0..L):  
g(x):=sum((p^i)*g[i](x),i=0..L):
HO1:=(1-p)*(diff(f(x),x,x))+p*(((1/x)*(diff(f(x),x))+Nb*((diff(f(x),x))*diff(g(x),x))+Nt(diff(f(x),x)^2))):                                                   
expand(%):                                                                                                                                          
collect(%,p):
HO2:=(1-p)*(diff(g(x),x,x))+p*(((1/x)*(diff(g(x),x))+(Nb/Nt)*((diff(f(x),x,x))+(1/x)*diff(f(x),x)))):                                                                                        
expand(%):                                                                                                               
collect(%,p):                                                                                                              
HO2:=%:                                                                                                                 
declare(f(x),g(x),prime=x): 
for i from 0 to L+1 do equa[1][i]:=coeff(HO1,p,i)=0 end  do:                                     
for i from 0 to L+1 do equa[2][i]:=coeff(HO2,p,i)=0 end  do:           
con[1][0]:=f[0](0)=(h(x)/64),(D(f[0]))(0)=0:                                                                                                                  
con[2][0]:=g[0](0)=-(k-h(x)^2/4),(D(g[0]))(0)=0: 
for j from 1 to L do:                                                                                                    
 con[1][j]:=f[j](0)=h(x),(D(f[j]))(0)=0:                                                                           
 con[2][j]:=g[j](0)=h(x),(D(g[j]))(0)=0:                                                                         
 end do;
for i from 0 to L do;                                                                                                     
dsolve({equa[1][i],con[1][i]},f[i](x));                                                                              
f[i](x):=rhs(%);                                                                                                         
 f[i](x):=evalf(%);                                                                                                          
dsolve({equa[2][i],con[2][i]},g[i](x));                                                                            
 g[i](x):=rhs(%);                                                                                                          
g[i](x):=evalf(%);                                                                                                         
end do; 
for u from 0 to L-1 do:                                                                                                
  f[u](_z1):subs(x=_z1,f[u](x));                                                                                    
 g[u](_z1):subs(x=_z1,g[u](x));                                                                                  
 f[u+1](x):=value(simplify(f[u+1](x)));                                                                         
   f[u+1](x):=simplify(%);                                                                                               
g[u+1](x):=value(simplify(g[u+1](x)));                                                                        
g[u+1](x):=simplify(%);                                                                                                
end do:  
f(x):=evalf(simplify(sum(f[n](x),n=0..L))); 
#### direct calculations                      
#direct solve the two equations in terms of f(x) and g(x) for h(x)=e^x where Nt and Nb #are parameters and its takes some values example 1,1
restart:
with(DETools):
with(plots):
with(IntegrationTools):
Nb:=1:Nt:=1:h(x):=e^x:
Eq1 := (diff(f(x),x,x))+(((1/x)*(diff(f(x),x))+Nb*((diff(f(x),x))*diff(g(x),x))+Nt(diff(f(x),x)^2))):   
Eq2 := (diff(g(x),x,x))+(((1/x)*(diff(g(x),x))+(Nb/Nt)*((diff(f(x),x,x))+(1/x)*diff(f(x),x)))):       

Cd1 := f(0) = h(x), (D(f))(0) = 0:
dsys := {Cd1, Eq1}:
dsol := dsolve(dsys, numeric, output = operator):
#dsol(.1):
plots[odeplot](dsol, [x, diff(f(x), x$1)], 0 .. 5, color = green):
Cd2 := g(0) = h(x), (D(g))(0) = 0:
dsys := {Cd1, Cd2, Eq1, Eq2}:
dsol := dsolve(dsys, numeric, output = operator):
plots[odeplot](dsol, [x, f(x)], 0 .. 5, color = red);
plots[odeplot](dsol, [x,g(x)], 0 .. 5, color = black);
                                                                         

This is the default style about the group of DrawSubgroupLattice:

DrawSubgroupLattice(SymmetricGroup(4))

But I hope to label the DrawSubgroupLattice with the order of the subgroup but not the default index, is it possible? I can get the order with this code:

GroupOrder~(SubgroupLattice(SymmetricGroup(4), output = list))

But I don't know how to label it into the node...

How to replace 7th-row(second last) of the matrix H116 (see eq. (14)) with the 1st-row of the matrix H16 (see eq. (15)) and create a new matrix of size same as H116?

matrixop.mw

I've run into a problem.  I'm trying to enter multiple quotes in a string.

for example

a:=[["{"test1","test2"}"],["{test3","test4"}"]]
                

How to plot F(R) for R=0..100 ?

Maple 2021 sheet attached.

Download How_to_plot_IR.mw

plot(F(R), R = 0 .. 100)

Hi! Can anyone show me a quick example of a procedure with local and global variables?!? It seems that i'm not getting the hang of it, because i keep receiving "unable to parse" messages. 

pointplot works with units, textplot apparently doesn't

Download Textplot.mw

restart;
read "C:/Program Files/Maple 2020/lib/ASP v4.6.3.txt";

    DESOLVII_V5R5 (March 2011)(c), by Dr. K. T. Vu, Dr. J.

       Carminati and Miss G. Jefferson

The authors kindly request that this software be referenced, if

   it is used in work eventuating in a publication, by citing

   the article:

  K.T. Vu, G.F. Jefferson, J. Carminati, Finding generalised

     symmetries of differential equations

  using the MAPLE package DESOLVII,Comput. Phys. Commun. 183

     (2012) 1044-1054.

                         -------------

 ASP (November 2011), by Miss G. Jefferson and Dr. J. Carminati

The authors kindly request that this software be referenced, if

   it is used in work eventuating in a publication, by citing

   the article:

     G.F. Jefferson, J. Carminati, ASP: Automated Symbolic

        Computation of Approximate Symmetries

   of Differential Equations, Comput. Phys. Comm. 184 (2013)

      1045-1063.

 [classify, comtab, defeqn, deteq_split, extgenerator, gendef,

   genvec, icde_cons, liesolve, mod_eq, originalVar, pdesolv,

   reduceVar, reduceVargen, symmetry, varchange]

                     ASP := _m2229977204928

with(ASP);
       [ApproximateSymmetry, applygenerator, commutator]

with(desolv);
 [classify, comtab, defeqn, deteq_split, extgenerator, gendef,

   genvec, icde_cons, liesolve, mod_eq, originalVar, pdesolv,

   reduceVar, reduceVargen, symmetry, varchange]

read "C:/Program Files/Maple 2020/lib/FracSym.v1.16.txt";
FracSym (April 2013), by Miss G. Jefferson and Dr. J. Carminati

The authors kindly request that this software be referenced, if

   it is used in work eventuating in a publication, by citing:

   G.F. Jefferson, J. Carminati, FracSym: Automated symbolic

      computation of Lie symmetries

   of fractional differential equations, Comput. Phys. Comm.

      Submitted May 2013.

with(FracSym);
[Rfracdiff, TotalD, applyFracgen, evalTotalD, expandsum, fracDet,

  fracGen, split]

Rfracdiff(u(x, t), t, alpha);
                          alpha          
                       D[t     ](u(x, t))

Rfracdiff(u(x, t) &* v(x, t), t, alpha);
infinity                                                          
 -----                                                            
  \                                                               
   )                          (alpha - n)              n          
  /     binomial(alpha, n) D[t           ](u(x, t)) D[t ](v(x, t))
 -----                                                            
 n = 0                                                            

Rfracdiff(v(x, t) &* u(x, t), t, alpha);
infinity                                                          
 -----                                                            
  \                                                               
   )                          (alpha - n)              n          
  /     binomial(alpha, n) D[t           ](v(x, t)) D[t ](u(x, t))
 -----                                                            
 n = 0                                                            

Rfracdiff(u(x, t) &* v(x, t), t, 2);
     /  2         \                                        
     | d          |             / d         \ / d         \
     |---- u(x, t)| v(x, t) + 2 |--- u(x, t)| |--- v(x, t)|
     |   2        |             \ dt        / \ dt        /
     \ dt         /                                        

                  /  2         \
                  | d          |
        + u(x, t) |---- v(x, t)|
                  |   2        |
                  \ dt         /

TotalD(xi[x](x, y), x, 2);
                          2              
                       D[x ](xi[x](x, y))

evalTotalD([%], [y], [x]);
     [     /  2             \     /   2              \    
     [   2 | d              |     |  d               |    
     [y_x  |---- xi[x](x, y)| + 2 |------ xi[x](x, y)| y_x
     [     |   2            |     \ dy dx            /    
     [     \ dy             /                             

                                   /  2             \]
               / d             \   | d              |]
        + y_xx |--- xi[x](x, y)| + |---- xi[x](x, y)|]
               \ dy            /   |   2            |]
                                   \ dx             /]

fde1 := Rfracdiff(u(x, t), t, alpha) = -u(x, t)*diff(u(x, t), x) - diff(u(x, t), x, x) - diff(u(x, t), x, x, x) - diff(u(x, t), x, x, x, x);
                alpha                      / d         \
     fde1 := D[t     ](u(x, t)) = -u(x, t) |--- u(x, t)|
                                           \ dx        /

          /  2         \   /  3         \   /  4         \
          | d          |   | d          |   | d          |
        - |---- u(x, t)| - |---- u(x, t)| - |---- u(x, t)|
          |   2        |   |   3        |   |   4        |
          \ dx         /   \ dx         /   \ dx         /

deteqs := fracDet([fde1], [u], [x, t], 2);
  Intervals/values considered for the fractional derivative/s:

                     {0 < alpha, alpha < 1}

          [                                           
          [                                           
          [[  2                                       
          [[ d                     d                  
deteqs := [[---- eta[u](x, t, u), --- xi[t](x, t, u),
          [[   2                   du                 
          [[ du                                       

   d                   d                   d                  
  --- xi[t](x, t, u), --- xi[t](x, t, u), --- xi[x](x, t, u),
   du                  dx                  du                 

                        2                    2                  
   d                   d                    d                   
  --- xi[x](x, t, u), ---- xi[t](x, t, u), ---- xi[t](x, t, u),
   du                    2                    2                 
                       du                   du                  

    2                                              
   d                         / d                \  
  ---- xi[t](x, t, u), alpha |--- xi[x](x, t, u)|,
     2                       \ dt               /  
   du                                              

                                2                  
        / d                \   d                   
  alpha |--- xi[x](x, t, u)|, ---- xi[t](x, t, u),
        \ du               /     2                 
                               du                  

    2                    2                    3                  
   d                    d                    d                   
  ---- xi[x](x, t, u), ---- xi[x](x, t, u), ---- xi[t](x, t, u),
     2                    2                    3                 
   du                   du                   du                  

    3                    3                    4                  
   d                    d                    d                   
  ---- xi[t](x, t, u), ---- xi[x](x, t, u), ---- xi[t](x, t, u),
     3                    3                    4                 
   du                   du                   du                  

    4                  
   d                   
  ---- xi[x](x, t, u),
     4                 
   du                  

     /  2                \                           
     | d                 |     / d                \  
  -6 |---- xi[t](x, t, u)| - 3 |--- xi[t](x, t, u)|,
     |   2               |     \ dx               /  
     \ dx                /                           

        / d                \     / d                \  
  alpha |--- xi[t](x, t, u)| - 4 |--- xi[x](x, t, u)|,
        \ dt               /     \ dx               /  

  / d                \              
  |--- xi[t](x, t, u)| (alpha - 1),
  \ du               /              

                               /   2                 \  
     / d                \      |  d                  |  
  -3 |--- xi[t](x, t, u)| - 12 |------ xi[t](x, t, u)|,
     \ du               /      \ dx du               /  

        / d                \              
  alpha |--- xi[t](x, t, u)| (alpha - 1),
        \ du               /              

        / d                \              
  alpha |--- xi[x](x, t, u)| (alpha - 1),
        \ du               /              

     /  2                \      /   3                  \  
     | d                 |      |  d                   |  
  -3 |---- xi[t](x, t, u)| - 12 |------- xi[t](x, t, u)|,
     |   2               |      |      2               |  
     \ du                /      \ dx du                /  

        /   2                 \              
        |  d                  |              
  alpha |------ xi[t](x, t, u)| (alpha - 1),
        \ du dt               /              

        /   2                 \              
        |  d                  |              
  alpha |------ xi[x](x, t, u)| (alpha - 1),
        \ du dt               /              

        /  2                \              
        | d                 |              
  alpha |---- xi[t](x, t, u)| (alpha - 1),
        |   2               |              
        \ du                /              

        /  2                \              
        | d                 |              
  alpha |---- xi[x](x, t, u)| (alpha - 1),
        |   2               |              
        \ dt                /              

        /  2                \              
        | d                 |              
  alpha |---- xi[x](x, t, u)| (alpha - 1),
        |   2               |              
        \ du                /              

   /  3                \     /   4                  \  
   | d                 |     |  d                   |  
  -|---- xi[t](x, t, u)| - 4 |------- xi[t](x, t, u)|,
   |   3               |     |      3               |  
   \ du                /     \ dx du                /  
                          /   2                 \
 / d                \     |  d                  |
-|--- xi[t](x, t, u)| - 4 |------ xi[t](x, t, u)|
 \ du               /     \ dx du               /

           / d                \     / d                \
   + alpha |--- xi[t](x, t, u)|, -4 |--- xi[x](x, t, u)|
           \ du               /     \ du               /

       /  2                 \      /   2                 \  
       | d                  |      |  d                  |  
   + 4 |---- eta[u](x, t, u)| - 16 |------ xi[x](x, t, u)|,
       |   2                |      \ dx du               /  
       \ du                 /                               
                            /  2                 \
   / d                \     | d                  |
-3 |--- xi[x](x, t, u)| + 3 |---- eta[u](x, t, u)|
   \ du               /     |   2                |
                            \ du                 /

        /   2                 \     /  3                \
        |  d                  |     | d                 |
   - 12 |------ xi[x](x, t, u)|, -4 |---- xi[t](x, t, u)|
        \ dx du               /     |   3               |
                                    \ dx                /

                                /  2                \  
       / d                \     | d                 |  
   - 2 |--- xi[t](x, t, u)| - 3 |---- xi[t](x, t, u)|,
       \ dx               /     |   2               |  
                                \ dx                /  
   /   2                 \      /   3                  \
   |  d                  |      |  d                   |
-6 |------ xi[t](x, t, u)| - 12 |------- xi[t](x, t, u)|
   \ dx du               /      |   2                  |
                                \ dx  du               /

       / d                \  
   - 2 |--- xi[t](x, t, u)|,
       \ du               /  

        / d                \                          
  alpha |--- xi[t](x, t, u)| (alpha - 1) (alpha - 2),
        \ du               /                          
   /  2                \     /  3                 \
   | d                 |     | d                  |
-6 |---- xi[x](x, t, u)| + 6 |---- eta[u](x, t, u)|
   |   2               |     |   3                |
   \ du                /     \ du                 /

        /   3                  \     /   3                  \
        |  d                   |     |  d                   |
   - 24 |------- xi[x](x, t, u)|, -3 |------- xi[t](x, t, u)|
        |      2               |     |      2               |
        \ dx du                /     \ dx du                /

       /    4                  \   /  2                \         
       |   d                   |   | d                 |        /
   - 6 |-------- xi[t](x, t, u)| - |---- xi[t](x, t, u)|, alpha |
       |   2   2               |   |   2               |        \
       \ dx  du                /   \ du                /         

   d                \     / d                \
  --- xi[t](x, t, u)| - 3 |--- xi[x](x, t, u)|
   dt               /     \ dx               /

       /   2                  \     /  2                \  
       |  d                   |     | d                 |  
   + 4 |------ eta[u](x, t, u)| - 6 |---- xi[x](x, t, u)|,
       \ dx du                /     |   2               |  
                                    \ dx                /  

        /   2                 \                          
        |  d                  |                          
  alpha |------ xi[t](x, t, u)| (alpha - 1) (alpha - 2),
        \ du dt               /                          

        /  2                \                          
        | d                 |                          
  alpha |---- xi[t](x, t, u)| (alpha - 1) (alpha - 2),
        |   2               |                          
        \ du                /                          
   /   2                 \     /   3                  \
   |  d                  |     |  d                   |
-3 |------ xi[t](x, t, u)| - 6 |------- xi[t](x, t, u)|
   \ dx du               /     |   2                  |
                               \ dx  du               /

                                                              /
     / d                \         / d                \        |
   - |--- xi[t](x, t, u)| + alpha |--- xi[t](x, t, u)|, alpha |
     \ du               /         \ du               /        |
                                                              \
       /  2                \     /   2                  \
       | d                 |     |  d                   |
-alpha |---- xi[t](x, t, u)| + 2 |------ eta[u](x, t, u)|
       |   2               |     \ du dt                /
       \ dt                /                             

     /  2                \\   /  3                \
     | d                 ||   | d                 |
   + |---- xi[t](x, t, u)||, -|---- xi[x](x, t, u)|
     |   2               ||   |   3               |
     \ dt                //   \ du                /

       /   4                  \   /  4                 \  
       |  d                   |   | d                  |  
   - 4 |------- xi[x](x, t, u)| + |---- eta[u](x, t, u)|,
       |      3               |   |   4                |  
       \ dx du                /   \ du                 /  
                          /  2                \
   / d                \   | d                 |
-u |--- xi[t](x, t, u)| - |---- xi[t](x, t, u)|
   \ dx               /   |   2               |
                          \ dx                /

     /  3                \   /  4                \  
     | d                 |   | d                 |  
   - |---- xi[t](x, t, u)| - |---- xi[t](x, t, u)|,
     |   3               |   |   4               |  
     \ dx                /   \ dx                /  

        /   3                  \                          
        |  d                   |                          
  alpha |------- xi[t](x, t, u)| (alpha - 1) (alpha - 2),
        |      2               |                          
        \ du dt                /                          

        /   3                  \                          
        |  d                   |                          
  alpha |------- xi[t](x, t, u)| (alpha - 1) (alpha - 2),
        |   2                  |                          
        \ du  dt               /                          

        /  3                \                          
        | d                 |                          
  alpha |---- xi[t](x, t, u)| (alpha - 1) (alpha - 2),
        |   3               |                          
        \ du                /                          
                            /  2                 \
   / d                \     | d                  |
-3 |--- xi[x](x, t, u)| + 3 |---- eta[u](x, t, u)|
   \ du               /     |   2                |
                            \ du                 /

       /   2                 \      /   3                   \
       |  d                  |      |  d                    |
   - 9 |------ xi[x](x, t, u)| + 12 |------- eta[u](x, t, u)|
       \ dx du               /      |      2                |
                                    \ dx du                 /

        /   3                  \                              
        |  d                   |        / d                \  
   - 18 |------- xi[x](x, t, u)|, alpha |--- xi[t](x, t, u)| u
        |   2                  |        \ du               /  
        \ dx  du               /                              

       /   3                  \     /   4                  \
       |  d                   |     |  d                   |
   - 3 |------- xi[t](x, t, u)| - 4 |------- xi[t](x, t, u)|
       |   2                  |     |   3                  |
       \ dx  du               /     \ dx  du               /

       /   2                 \                                  
       |  d                  |   / d                \          /
   - 2 |------ xi[t](x, t, u)| - |--- xi[t](x, t, u)| u, alpha |
       \ dx du               /   \ du               /          \

                          /  3                \
   d                \     | d                 |
  --- xi[t](x, t, u)| - 4 |---- xi[x](x, t, u)|
   dt               /     |   3               |
                          \ dx                /

       /  2                \                         
       | d                 |     / d                \
   - 3 |---- xi[x](x, t, u)| - 2 |--- xi[x](x, t, u)|
       |   2               |     \ dx               /
       \ dx                /                         

       /   3                   \     /   2                  \  
       |  d                    |     |  d                   |  
   + 6 |------- eta[u](x, t, u)| + 3 |------ eta[u](x, t, u)|,
       |   2                   |     \ dx du                /  
       \ dx  du                /                               
 /  2                \   /  3                 \
 | d                 |   | d                  |
-|---- xi[x](x, t, u)| + |---- eta[u](x, t, u)|
 |   2               |   |   3                |
 \ du                /   \ du                 /

       /   3                  \     /   4                   \
       |  d                   |     |  d                    |
   - 3 |------- xi[x](x, t, u)| + 4 |------- eta[u](x, t, u)|
       |      2               |     |      3                |
       \ dx du                /     \ dx du                 /

       /    4                  \              /
       |   d                   |              |
   - 6 |-------- xi[x](x, t, u)|, (alpha - 1) |
       |   2   2               |              |
       \ dx  du                /              \
       /  3                \     /   3                   \
       | d                 |     |  d                    |
-alpha |---- xi[t](x, t, u)| + 3 |------- eta[u](x, t, u)|
       |   3               |     |      2                |
       \ dt                /     \ du dt                 /

       /  3                \\                               
       | d                 ||           / d                \
   + 2 |---- xi[t](x, t, u)|| alpha, -u |--- xi[x](x, t, u)|
       |   3               ||           \ du               /
       \ dt                //                               

     /  2                 \     /   2                 \
     | d                  |     |  d                  |
   + |---- eta[u](x, t, u)| - 2 |------ xi[x](x, t, u)|
     |   2                |     \ dx du               /
     \ du                 /                            

       /   3                   \     /   3                  \
       |  d                    |     |  d                   |
   + 3 |------- eta[u](x, t, u)| - 3 |------- xi[x](x, t, u)|
       |      2                |     |   2                  |
       \ dx du                 /     \ dx  du               /

       /   4                  \     /    4                   \  
       |  d                   |     |   d                    |  
   - 4 |------- xi[x](x, t, u)| + 6 |-------- eta[u](x, t, u)|,
       |   3                  |     |   2   2                |  
       \ dx  du               /     \ dx  du                 /  
   / d                \                  
-u |--- xi[x](x, t, u)| + eta[u](x, t, u)
   \ dx               /                  

                                      /   2                  \
           / d                \       |  d                   |
   + alpha |--- xi[t](x, t, u)| u + 2 |------ eta[u](x, t, u)|
           \ dt               /       \ dx du                /

     /  2                \     /   3                   \
     | d                 |     |  d                    |
   - |---- xi[x](x, t, u)| + 3 |------- eta[u](x, t, u)|
     |   2               |     |   2                   |
     \ dx                /     \ dx  du                /

     /  3                \     /   4                   \
     | d                 |     |  d                    |
   - |---- xi[x](x, t, u)| + 4 |------- eta[u](x, t, u)|
     |   3               |     |   3                   |
     \ dx                /     \ dx  du                /

                             [                          
                             [                          
     /  4                \]  [                          
     | d                 |]  [                          
   - |---- xi[x](x, t, u)|], [xi[t](x, 0, u) = 0, (Diff(
     |   4               |]  [                          
     \ dx                /]  [                          

                                   / d                 \
  eta[u](x, t, u), t $ alpha)) + u |--- eta[u](x, t, u)|
                                   \ dx                /

       /    / d                            \\
   - u |Diff|--- eta[u](x, t, u), t $ alpha||
       \    \ du                           //

     /  3                 \   /  4                 \
     | d                  |   | d                  |
   + |---- eta[u](x, t, u)| + |---- eta[u](x, t, u)|
     |   3                |   |   4                |
     \ dx                 /   \ dx                 /

                             /infinity                             
                             | -----                               
     /  2                 \  |  \                                  
     | d                  |  |   )    /    1   /                   
   + |---- eta[u](x, t, u)|, |  /     |- ----- |binomial(alpha, n)
     |   2                |  | -----  \  n + 1 \                   
     \ dx                 /  \ n = 3                               

  /   (alpha - n)              (n + 1)                       
  |D[t           ](u(x, t)) D[t       ](xi[t](x, t, u)) alpha
  \                                                          

        (alpha - n)              (n + 1)                   
   - D[t           ](u(x, t)) D[t       ](xi[t](x, t, u)) n

        (alpha - n) / d         \    n                   
   + D[t           ]|--- u(x, t)| D[t ](xi[x](x, t, u)) n
                    \ dx        /                        

                                                          \   /Sum(
                                                          |   |    
                                                          |   |    
        (alpha - n) / d         \    n                 \\\|   |    
   + D[t           ]|--- u(x, t)| D[t ](xi[x](x, t, u))|||| + |    
                    \ dx        /                      ///|   |    
                                                          /   \    

                     /    / d                        \\
  binomial(alpha, n) |Diff|--- eta[u](x, t, u), t $ n||
                     \    \ du                       //

     (alpha - n) (u(x, t)), n = 3 .. infinity)\]  
  D[t           ]                             |]  
                                              |]  
                                              |]  
                                              |],
                                              |]  
                                              /]  

                                                              ]
                                                              ]
                                                              ]
                                                              ]
  [xi[x](x, t, u), xi[t](x, t, u), eta[u](x, t, u)], [x, t, u]]
                                                              ]
                                                              ]

sol1 := pdesolv(expand(deteqs[1]), deteqs[3], deteqs[4]);
Error, (in desolv/lderivx) cannot determine if this expression is true or false: 1 < x |C:/Program Files/Maple 2020/lib/ASP v4.6.3.txt:4312|