How to explain the difference in the outputs of

restart; ans1 := solve(eval({-4*a^2+x^2+y^2 <= 8*y-10*x+4*a-40, -a^2+x^2+y^2 <= 6*x-4*y-13}, a = -9), {x, y});
ns1 := {x = 3-sqrt(-y^2-4*y+77), -11 <= y, y < 13/25},
 {-11 < y, x < -5+sqrt(-y^2+8*y+273), y < 13/25, 3-sqrt(-y^2-4*y+77) < x}, 
{x = -5+sqrt(-y^2+8*y+273), -11 < y, y < 13/25}, {y = 13/25, -141/25 <= x, x <= 291/25},
 {x = 3-sqrt(-y^2-4*y+77), y <= 7, 13/25 < y}, 
{13/25 < y, x < 3+sqrt(-y^2-4*y+77), y < 7, 3-sqrt(-y^2-4*y+77) < x}, 
{x = 3+sqrt(-y^2-4*y+77), 13/25 < y, y < 7}

and

restart; ans2 := solve(eval({-4*a^2+x^2+y^2 <= 8*y-10*x+4*a-40, -a^2+x^2+y^2 <= 6*x-4*y-13}, a = -9), [x, y]);
ans2 := [[x < 3, -6 <= x, y = -2-sqrt(-x^2+6*x+72)], 
[x < 3, -6 < x, y < -2+sqrt(-x^2+6*x+72), -2-sqrt(-x^2+6*x+72) < y], 
[x < 3, -6 < x, y = -2+sqrt(-x^2+6*x+72)], [x = 3, y <= 7, -11 <= y],
 [x <= 291/25, 3 < x, y = 4-sqrt(-x^2-10*x+264)],
 [x < 291/25, 3 < x, y < -2+sqrt(-x^2+6*x+72), 4-sqrt(-x^2-10*x+264) < y],
 [x < 291/25, 3 < x, y = -2+sqrt(-x^2+6*x+72)]]

?

In the former x is expressed through y and in the latter y is expressed through x. I find explanation  in neither ?solve nor ?solve,details.

can anyone one tell me the meaning of builtin with examples?

A:={4,5,6,-9};
                          A := {4, 5, 6, -9}

E:={a,a,-2,4,-6};
                         E := {-2, 4, -6, a}

how does maple treat sets , and  what is the diffrence between sets and lists ?

Hi MaplePrimes Web managers

I suspect you have forgotten to update the lists for MapleSim "2017" you seem to stop at "MapleSim 2016", while I hear from your local office that MapleSim 2018 is "just around the corner" ...
It would make it easier to sort the issues for the last version, no ?

Thanks for your support
Sincerely
Ivar

restart;
with(DEtools);
assume(r::real, a::real, b::real, upsilon::real, sigma::real, x::real, y::real, t > 0);
assume(sigma > 0); assume(-b^2-r+2 > 0);
V := -2*exp(I*(sqrt(-b^2-r+2)*x+b*y+r*t))*sqrt(1/sigma)*sech(-t*(-2*sqrt(-b^2-r+2)-2*b)-x-y):
pde[1] := I*(diff(V, t))+diff(V, x, x)+diff(V, y, y)+sigma*abs(V^2)*V = 0: evalc(pde[1]);

solution.mw

Dear All

I seldom need support, Maple/MapleSim usually runs OK, but here I'm stuck with MapleSim 2017 I'm modelling some thermal fluid properties and each time I make a sub-system I get two errors:

1) the entries (and exit variables) "rho, Cp, Cv, lambda, and nu" of my models are set to default "1" instead of my expected value the names of my fluid-parameter items. I must rename them by hand to be able to solve my model, why not a link to the fluid parameter node ?

2) I get a pressure p (or is it a "rho"?) issue: "Cannot resolve `Main.Block1.p`; there is no `p` in variable `Main.Block1`" when I create a sub-system I call here Block1 and my model does not solve if I make any "sub-systems", and I cannot find out what to do, is this an initial value issue ? the error message could be more helpful ;)

Any clues how to get around this ?

Thnaks in avance

Sincerely

Ivar

I do not know what I am doing wrong. I am trying to plot each of the solutions to an ODE. One of the solutions Maple gives is  LegendreQ((1/2)*sqrt(5)-1/2, x) and the other is LegendreP((1/2)*sqrt(5)-1/2, x)

Maple can plot the  LegendreP, but gives an error plotting LegendreQ((1/2)*sqrt(5)-1/2, x)

ode:=(1-x^2)*diff(y(x),x$2)-2*x*diff(y(x),x)+y(x)=0:
sol:=dsolve(ode,y(x));

sol := y(x) = _C1*LegendreP((1/2)*sqrt(5)-1/2, x)+_C2*LegendreQ((1/2)*sqrt(5)-1/2, x)

Now when I do 

plot(LegendreQ((1/2)*sqrt(5)-1/2, x),x=-1..1);

Maple says

Warning, unable to evaluate the function to numeric values in the region; see the plotting command's help page to ensure the calling sequence is correct
 

Why is that? I tried x=-0.5..1 and x=0.5..1 and keep getting same error message. It works ok for 

plot(LegendreP((1/2)*sqrt(5)-1/2, x),x=-1..1);

Mathematica can plot both with no problem.

Dear all

Represent

x+(( y^(2+x) )-4)/3

as a binary tree and rewrite this expression in postfix notation

Can this quesiton be solved using maple

Many thanks

the graph of tan (x) and the graph of the tangent line ( at pi/4). the graph of arctan x, and the graph of the tangent line of arctan x at x=1.

4 graphs (on the same set of axis)

Hi Users!

Hope everyone in fine and enjoying good health. I am facing problem to differential the following expression with respect to first variable (mentioned as red). Please help me to fix this query

f(z*sqrt(a/nu[f]), U*t/(2*x))

Thanks in advance

create the sequence of exp (((aπ) / b)) for a varying from 1 to 15 and b varying from 1 to 10.

Hey.
I have been trying to convert my maple .mw file to a PDF under 'Print...' but it does not work. The problem is when I click on the "Save as PDF" and I name my pdf and click on 'Save' it does not save my file anywhere. It simply will not save it. 
Does somebody know why it will not save as a PDF? It saves all other files properly (also converts word files to PDF fine). 

Can I somehow define a function based on a result from a PolynomialFit.
It doesn't seem to read it as a function the way I try to define it now (see attached maple file).

I could copy the result into a function, but then I lose some information since the values are approximated.

Define.mw