@Preben Alsholm These links cover the univariate case only.

@john125 Can you post a worksheet with the actual equations, please?

@john125 Sorry, I meant

select(y-> is(y>0), [Sols]);

@toandhsp Cut and pate Kitonum's code directly from the Post.

@acer Why are your exponents off by 4 decimal places compared to the OP's?

@toandhsp Did you get no result, or did you get a RootOf result? If the latter, add the explicit option to the command:

solve({30+1144*r^4-832*r^2=0, r>0}, explicit);

@ctnaz I know that *F means multiply by F, but you have "*F" not *F. What is the purpose of the quotation marks?

@Preben Alsholm

Saying the same thing differently, in a way that seems clearer to me: Reading the file with read is equivalent to executing b:= 2*z at the global level, regardless of where the read statement is placed.

I recall reading this in a help file, but I can't find it at ?read or ?parse. Preben, can you find it in help?

I also believe that reading a text file (as opposed to a .m file) with read is equivalent to applying parse to the file's contents, but I can't find this in help.

Indeed, MaplePrimes should have a rule that you need a certain level of reputation in order to Edit Questions after they have Answers!

@Markiyan Hirnyk It can't be a comment to your Answer because I wrote it before reading your Answer.

@Markiyan Hirnyk I show that erf(10.) is the source of the problem and that the erroneous value is exactly 100*sqrt(Pi). I also show the value of using exact arithmetic from the very start.

@acer In particular, you've changed the range of r from 2.5..4 to 0..0.4 and the range of x from 0..1 to 0..2. How did you know exactly how to change them?

@emmantop Your file didn't upload properly. Can you try uploading again?

Maple is saying that you need two more initial conditions. Can you come up with two more?

@ctnaz Your code contains this line, which makes no sense to me:

F[k+2]:=( sum(F[r]"*F"[k-r],r=0..k)+sum(G[r]*G[k-r],r=0..k)+sum((k-r+1)*H[r]*F[k-r+1],r=0..k)+M*F[k])*k!/(k+2)!:

What is the "*F" supposed to mean?