Apologies for possible double post, it seemingly locked up upon trying to post the first time. 

So before I get as far as to ask for how to get a certain PDE system solved and plotted, I tried to fiddle a little bit around with linear algebra. 

• First, the file SystemGoesWrong.mw . I have issues with declaring (same result if I remove the with(VectorCalculus)); as far as I can see, EQ0 and EQ00 should be the same, except that I have summed the vector in one of them. And the first that "works", is wrong: it returns a scaling of a vector. How come?
• But then I copy everything from the heading and down into a worksheet where I was already fighting some linear algebra things (can someone please explain?): SystemDeclaresBut.mw 
  Then EQ0 and EQ00 declare just fine! What is the issue?
• How do I get Maple to list the equations in "compact" form with vector-valued functions so that I can read and debug?  The actual PDE system I want to solve (numerically, of course), looks as follows: DE4Maple.pdf 
  That was also the reason why I tried to declare procedures (coordinate-wise maximum ...), but I guess that questions on how to extract a solution and plot it in a particular way will be its own posting after I have learned how to declare it.

The contents of the first file:

Download SystemGoesWrong.mw

... and of the second:

Download SystemDeclaresBut.mw

Suppose that I make a simple plot, of a function f(x), such as  p1 := plot( 2*x+1,x=0..4,numpoints=9);

Then logically, the plot p1 contains a table with values (x, f(x)) which are plotted.

HOW can I extract that table of values from the plot p1, and write it to a data file (simple text file), so that I can process the data elsewhere (for example, for making a professional graph from them).

I had scripts who did this up to Maple 13 (or Maple V release 13, if that is the politically correct version), but they do not work anymore with more recent versions.

Many thanks !!

Malte.

first question:

Define a two point distribution:
f1(x):=piecewise(x = 0, 0.3, x = 0.1, 0.7, 0)

Dist1 := Distribution(PDF = f1)

R1 := RandomVariable(Dist1)

Mean(R1)

Why Mean(R1) gives 0? should be 0.07...

If I managed to define antother discrete point distribution say R2. Can I define R:=R1+R2 and then caculate Mean(R) or even plot PDF of R?

I solved a system of differential equations and want to declare an integral with variable upper limit ( T(x) ) from a function I got from the system ( r(x) ). I did so, but Maple doesn't recognise it as a function of one variable, because when I put this T(x) into a system, it gives me an error:

Error, (in dsolve/numeric/process_input) input system must be an ODE system, got independent variables {t, x}

Though there is no t in the system, t was an integration variable when I declared T(x).

Where is the mistake?

2.mw

In LPSolve, I have solutions returned in matrix form that contain elements that are negligible (values close to zero).

Is there a simple way to convert and reduce these values to zero in the matrix (rather than return the exact values)?

Thanks! 

Is there a way that I can obtain a plot of a set of points like {(2,4),(3,5),(4,7),(5,8),(6,11)} in the domain of the set of positive integers. And the codomain is also the set of positive integers?

And after that is it possible to obtain a polynomial interpolation for three of the points say (2,4),(3,5) and (4,7)?

Thanks a lot in advance.

Hello,
How to find the points indicated in the graph of the following function:
(1.25 * y-sqrt (abs (x))) ^ 2 + x ^ 2-1,

I have used the Taks: the Second Derivative Test. Without results, as I show below:

Heart_Critical_Points_and_the_Second_Derivative_Test.mw
 

Download Heart_Critical_Points_and_the_Second_Derivative_Test.mw

Hey. I can't seem to implement the following recursive (piecewise) function:

f:=n->piecewise(n=0,1,n>=1,sum(f(k),k=0..n-1))

This doesn't work..How do I make it work? :( 

Spawned from here.

1. series() shows some strange dependence on the session history, the first call breaking subsequent computations. Also, for F(x, y), the zeroth term is RootOf(F(0, _Z)), even though 1 is the only solution, but for G(x, y), RootOf(G(0, _Z)) is evaluated to 1, even though 1 is not the only solution:

F := (x, y) -> ln((1+x)*y)+exp(x^2*y^2)-x-cos(x):
G := (x, y) -> ln((1+x)*y)+exp(x^2+y-1)-x-cos(x):

series(RootOf(G(x, y), y), x = 0, 5);
                 1-(1/2)*x^2-(1/6)*x^3+(7/48)*x^4+O(x^5)

series(RootOf(G(x, y), y), x = 0, 6);
Error, (in series/RootOf) unable to compute series

forget(series);
series(RootOf(G(x, y), y), x = 0, 6);
           1-(1/2)*x^2-(1/6)*x^3+(7/48)*x^4-(1/60)*x^5+O(x^6)

series(RootOf(F(x, y), y), x = 0, 1);
                         RootOf(ln(_Z)) + O(x)

2. For some reason solve hangs the first time, then returns a result quickly, and apparently doesn't go along well with simplify, because the last output contains an escaped local variable ans. Besides, I'm not sure why solve generates a huge answer. Is it expanding something to a high order? I was expecting just RootOf(_Z+tan(_Z))+O(x).

ser := series(y+tan(y)+x, x = 0, 1);

iser := timelimit(30, solve(ser, y)): # appears to run indefinitely without timelimit
Error, (in ArrayTools:-NumElems) time expired

iser := solve(ser, y): # returns immediately

evalf(iser); # OK
                                             O(x)

evalf(simplify(iser)); # less OK
       .1250000000*(eval(RootOf(_Z+tan(_Z)), [RootOf = ans, tan(_Z) = sin(_Z)/cos(_Z)]))+O(x)

This is in Maple 2017.3.

Hi,

What is the procedure to follow for importing a maple file into Mobius?

Thanks

a := powseries:-powsolve(diff(f(z), z)-f(z)/z = 0);

seq(a(i), i = 0 .. 5);
                        0, 0, 0, 0, 0, 0

Seems that powsolve is constructing the relation k*a(k)-a(k) = 0 and solving it as a(k)=0. I think powsolve should detect such cases (regardless of whether or not they're supported).

Hi

II ve managed to build an expression with one variable 
I me trying to plot this expression on a defined range but maple doesn t not let me.

How do I manage to plot this expression ?

If you have any advise on how to improve my code I m open to comments 

Thanks a lot in advance
 

Download HW1_-_EC2_strain-pressure_graph.mw
 

Download HW1_-_EC2_strain-pressure_graph.mw

This is my first time in this forum, so I hope I use the correct conventions. If not please notice me. 

1. When a light body orbits a heavy body under the influence of gravity (e.g. a planet around the Sun), Newton’s laws show that the orbit is restricted to a two-dimensional plane and is given by the differential equation

   d²/d(φ)²(1/r(φ)) + 1/r(φ) = GM/h²

   Here, (r, φ) is the path of the light body in polar coordinates, M is the mass of the heavy body, G is the gravitational constant, and h is a constant related to the angular velocity of the light body (h = r²φ ̇). The heavy body can be considered to be approximately stationary and located at the origin.

   Use Maple to solve this differential equation numerically, taking M = 1, G = 1, h = 1 with initial conditions

   r(0)=2/3, r′(0)=dr/dφ (0) = 0

   Using polar coordinates, create a plot of the orbit (r(φ), φ) for
   0 ≤ φ < 2π. You should observe a perfect ellipse.

2. Since I am not a frequent maple user, I hope somebody can help me here

0=(1−p)π+φV+δR−(μ+λ+ϑ)S

0=pπ+ϑS−(μ+ϵλ+φ)V

0=ρλS+ρϵλV+(1−q)ηI−(μ+β+χ)C

0=(1−ρ)λS+(1−ρ)ϵλV+χC−(μ+α+η)I

0=βC+qηI−(μ+δ)R

Anybody know how to solve using coding for all the variable S,V,C,I,R

 I am trying to solve 2 equations in maple:

 1/  solve({1<x or x<3 or x>5});

 {x=x}    solution is correct

 2/  solve({1<x or x<3 or x<5});

 {x<5}    solution is wrong

 How do I have solution correct is {x=x} in Maple?

 Please teach me about this.

 Thank you very much!