@as5987 

If you say Sol[2,1] and Sol[2,2] then you are explicitly selecting the second point! If you want the first point, then use Sol[1,1] and Sol[1,2]. But why don't you use my selection procedure?

Which intersection do you want: the (setwise) intersection of two bases or a basis for the subspace which is the intersection of the subspaces spanned by two bases? There is hardly any practical value to the former, so I think that you want the latter, which is what is returned by IntersectionBasis. But don't conflate this with Maple's setwise intersect operator.

Please show some actual code so that I can give you better advice.

@as5987 

The initial arguments to display must be plot structures, not something arbitrary like [3,5].

plot_circle:= plot([r*cos(t), r*sin(t), t= -Pi..Pi]):
plots:-display:= (plot_circle, view= [-10..10, -10..10]);

Could you provide some more details, perhaps a small example done by hand?

@as5987 

Point2:= [3,5]:
r:= evalf(sqrt(`+`((Point2^~2)[]))):
plot([r*cos(t), r*sin(t), t= 0..2*Pi]);

@k20057 5 

I don't know what you mean. Is this it?

n:= 5:
'R()' $ n;

@Markiyan Hirnyk 

Yes, that's why I called it a simulation.

But it does prove that if the question has a unique answer, then that answer must be 4.

Do you even have access to Maple? Haven't you learned from your previous Questions and their Answers how to enter a matrix and find its reduced row-echelon form with Maple?

Putting "quick help please!" in your titles does not help your case. It makes you seem like someone who is not even trying to do their homework.

There is no ODE system shown in your Question. Perhaps you meant to attach a file?

@msurov 

I did not realize that you wanted to extract the constant term. It is also not clear whether it should come at the beginning or end of the list. The constant term can be extracted with tcoeff.

seq(coeff(eq,v), v= vars), tcoeff(eq);

GenerateMatrix also works well.

@taro 

algsubs generally cannot be used to substitute things that are algebraically equivalent. Consider the following two examples:

algsubs(x^2-1= (x+1)*(x-1), (x-1)*(x^2-1));

algsubs(x^2-1= (y+1)*(y-1), (x-1)*(x^2-1));

By the way, the code op(ex)[1] is not robust; it fails when ex has only one operand. You should use op(1, ex) instead.

@toandhsp In my code, PLk is the list of all pairs of tangents that aren't perpendicular. There is no pair that is repeated.

Please attach a worksheet containing the above code. You can attach a worksheet to a post by using the green up-arrow, whch is the last item on the second row of the toolbar in the MaplePrimes editor.

Please post a worksheet showing the error message. You can attach a worksheet to a post by using the green up-arrow, which is the last item on the second row of the toolbar in the MaplePrimes editor.

@cloz54 Here's how it works:

indets takes an expression and a type and returns a set of all subexpressions of the given type.

specfunc(anything, RootOf) is the type. It stands for "specific function". The anything means to look for functions named RootOf with arguments of type anything.

The [1] is to select the first RootOf in the set returned by indets, in case there is more than one.

op stands for "operands". When passed a function, op returns its argument(s).