@Joe Riel Vote up. I think that that last line should be

select(type, sols, set(name = posint));

@Sagar No. Even the integral int(sin(x)/x, x= 0..L) can't be expressed as an elementary function.

@Preben Alsholm I was only referring to your last two examples when I brought up the thing about named expression sequences. I only brought it up because it's the one way that `?[]` isn't equivalent to (A, index::list)-> A[index[]]. It's impossible to create a user-defined procedure that takes a seq(anything) as its first argument and has a second argument.

@Oliver Brumberg See this Wikipedia article: Welch's t-test.

@stefano91 Like I said before, you need to eliminate (I mean remove) the line x:= 0..Xa. It's the fourth line in the code you showed.

@Oliver Brumberg The degrees of freedom in the two-sample t-test is not necessarily integer. In this case it's 7.503828483920367. Did you take that into account in your hand calculation?

@Art Kalb I was suggesting that you use the unwindK that is documented on the same help page. But in order to say exactly how to use it, I'd need to see one of your actual problems.

@archstevej Did you copy-and-paste my code exactly? In particular, are you sure that you capitalized Arrayin the dsolve? The error that you report is exactly what would happen if you used array instead of Array.

@candemirx90 You wrote:

Another question is that is it possible to get a symbolic solution of each variable as well?(x= ...y + ...z +...) In other words can we solve the equations for every variable with another command? or isolate it for every variable?

The command is eliminate, as in

eliminate({eq||(1..3)}, {x});

[{x = 2903/8+(1/8)*y-(1/80)*z}, {6500*y^2-20*y*z+6401*z^2+5593400*y-2351340*z+733056100, 133225*y^2-206250*y*z+198225*z^2+47813600*y-23100000*z+1565019904}]

@Earl There's a little bit of documentation of `?[]` at ?use and more in the Maple Programming Guide. It's essentially equivalent to (A, index::list)-> A[index[]] except that it's built into the kernel and thus it can take a named expression sequence as its first argument. So, for example, if you had a list of lists LoL and you wanted a list of the last elements of each list, you could use map(`?[]`, LoL, [-1]).

What's the discrepancy to which you refer? A higher confidence means a wider interval.

@Don_Caraota DirectSearch must be downloaded from the Maple Applications Centre. See this post of mine.

@Kitonum Vote up.

Something closer to the original matrix notation can be achieved by

A:= Matrix((2,2), symbol= a):
B:= <-1,  2;
           3,  4>:
C:= <-1,  0;
           4, -5>:
seq(eval(A,s), s= evalf(allvalues(solve(convert(A^2+B.A+C, set)))));

or, in the case that there are variables other than those in A, make the last line

seq(eval(A,s), s= evalf(allvalues(solve(convert(A^2+B.A+C, set), convert(A,set)))));

@vv I think that that should be

plots[odeplot](de, [x, diff(y(x),x)^2 - 1], x=0..1);

@stefano91 Your error message is caused by unbalanced parentheses. The right parenthesis at the end has no corresponding left parenthesis. It was intended to be matched with abs(.

You'll need to eliminate the line x:= 0..Xa.

To minimize, don't change maximize to minimize as I suggested earlier. Just remove maximize; the default is to minimize.