MaplePrimes Questions

I'm new to Maple, and want to know what is the simpliest way to create additional electrical units like MVA and MVAr?

 

On the segment x ∈ [0,10] plot the numerical solution of the equation y '+ y = 2xsiny, satisfying the initial condition y (0) = 1.
What is wrong here? My solution:

I want to write a procedure called Resistance which calculates and displays the equivalent resistance to three resistors R1, R2 and R3

If the resistances are connected in series then Rser = R1 + R2 + R3

If the resistances are connected in parallel then (R1 * R2 * R3) / (R1 * R2 + R1 * R3 + R2 * R3) and after that, I must write an algorithm which I will test this resistance but it does not work please help me
 

"Resistance:=proc(R1,R2,R3) local Rser,Rpar,R; if(R=Rser)then Rser:=R1+R2+R3;   elif(R=Rpar)jthen Rpar:=(R1*R2*R3)/((R1*R2+R1*R3++R2*R3));  end if;  end proc;"

Error, unable to parse

"Resistance:=proc(R1,R2,R3) local Rser,Rpar,R; if(R=Rser)then Rser:=R1+R2+R3;   elif(R=Rpar) jthen Rpar:=(R1*R2*R3)/(R1*R2+R1*R3++R2*R3);  end if;  end proc;"

 

R1 := readstat(entrer*la*valeur*de*R1); R2 := readstat(entret*la*valeur*de*R2); R3 := readstat(entrer*la*valeur*de*R3); Resistance(R1, R2, R3); printf("la valeur en serie est:%f", Rser); printf("la valeur parallele est:%f", Rpar)

``


 

Download RESISTANCE.mw

Hello

I'm using the package DifferentialGeometry with Maple 2019. I have 2 questions whose answer I've not found in the Help section:

a) If I have a 2-form omega with d(omega)=0, how can I obtain the 1-form alpha such that d(alpha) = omega?

b) if alpha is a 1-form and X a vector field, how can I calculate alpha(X)?

Thanks Nicola

  Hello: 
    As a first step to my question, let  G be  a graph and  I'd like to know  whether it contains a C4 (cycle of 4) as its subgraph.
     For example: .   it contains C4.  So  program may be return true.  
    I'm most concerned about the following thing ( it is important problem for me, since in graphtheory, we usually consider some class graphs contain no sepecific graph ) :
   1 Further , I want to  get all connected graphs of order less than 6  which  contains no C4 .
   2 More generally, I want  to konw  a graph  whether contains some graph as its subgraph.For example : does it contain K4CompleteGraph(4)K32  CompleteGraph(3, 2)  and so on ?
    I read the  function subgaph.  But  It didn't solve my problem. Many thanks for your help or advise.
   # I  just know there is a function  IsTriangleFree which test if graph is triangle-free ( graph comtains no C3 in Maple 2019. I think my question and how to program may be  meaningful.

Hi, 

I found that using the packages heometry and simplex in the same worksheet (only one restart at the top of it) causes a conflict in the command simplex:-convexhull(`some set of points`, option = area).

It seems that Maple doesn't confounds  that area in the option=area  with geometry:-area
Is it possible to fix this?


 

restart:

L := { [0,0], [1/2,1/2], [1,1], [2,0], [1,0], [1,1/2] };
simplex:-convexhull(L, 'output'='area');

{[0, 0], [1, 0], [1, 1], [1, 1/2], [2, 0], [1/2, 1/2]}

 

1

(1)



Use of package geometry
 

restart

with(geometry):

triangle(T, [point(A,0,0), point(B,2,0), point(C,1,3)]):  # just an example

L := { [0,0], [1/2,1/2], [1,1], [2,0], [1,0], [1,1/2] };
simplex:-convexhull(L);
simplex:-convexhull(L, 'output'='area');

{[0, 0], [1, 0], [1, 1], [1, 1/2], [2, 0], [1/2, 1/2]}

 

[[0, 0], [2, 0], [1, 1]]

 

Error, invalid input: simplex:-convexhull expects its 2nd argument, opts, to be of type identical(output) = {list({identical(area, hull, plot)}), identical(area, hull, plot)}, but received output = geometry:-area

 



To avoid this conflict between 'output'='area' and geometry:-area I did this
 

restart

geometry:-triangle(T, [point(A,0,0), point(B,2,0), point(C,1,3)]):

triangle: 0 < -point(A 0 0)+point(B 2 0)+point(C 1 3)

Error, (in geometry:-triangle) not enough information: the triangle is not defined

 

L := { [0,0], [1/2,1/2], [1,1], [2,0], [1,0], [1,1/2] };
simplex:-convexhull(L);
simplex:-convexhull(L, 'output'='area');

{[0, 0], [1, 0], [1, 1], [1, 1/2], [2, 0], [1/2, 1/2]}

 

[[0, 0], [2, 0], [1, 1]]

 

1

(2)

 


 

Download geometry_vs_simplex.mw

Dear all,

I have the following metric

Is there any way to make the terms dt dphi and dphi dt not symmetric?

Denis

 

 

Calculate  where the domain Ω is bounded by the surfaces x + y + z = 1, x = 0, y = 0, z = 0.

What am I doing wrong?

Task: Calculate   where Ω is the part of a circle of radius a centered at
point O (0; 0), lying in the first quarter.

My attempt to solve:

What values need to be taken instead of infinity?

Dear all,

 

I need a Maple sheet or algorithm in order to solve the enclosed problem (myproblem.pdf . )

 

Thanks for your meaningful help.

 

Eric

 

I was wondering why Maple hangs on this first order heat pde (waited for more than 15 minutes)

pde:= diff(u(x,t),t)= diff(u(x, t), x$2) - 9*diff(u(x,t),x);
bc:=u(0,t)=0,u(1,t)=0;
ic:=u(x, 0) = exp(45/10*x)*(5*sin(Pi*x) + 9*sin(2*Pi*x) + 2*sin(3*Pi*x));
#infolevel[pdsolve]:=3;
pdsolve([pde,ic,bc],u(x,t))

It shows it hangs here:

Trying HINT = _F1(x)*_F2(t)
                           Trying given functional HINT ...
                     Third set of solution methods successful

Mathematica solves this very quickly and returns

heqn = D[u[x, t], t] == D[u[x, t], {x, 2}] - 9*D[u[x, t], x];
ic = u[x, 0] == Exp[45/10 x]*(5 Sin[Pi*x] + 9 Sin[2*Pi*x] + 2 Sin[3*Pi*x]);
bc = {u[0, t] == 0, u[1, t] == 0};
sol = DSolve[{heqn, ic, bc}, u[x, t], {x, t}]

I am asking becuase Maple normally have no problem with such PDE's so I was surprised it hangs on this one and was trying to find out why.

Other than using infolevel[pdsolve]:= what other tools should one try to debug where exactly it hangs and why?

Maple 2019, Physics V 350

Yo I have fit a surface to a curve using polynomial regression:

(It's only supposed to be fit for negative t domain)

Now I've attempted to cap this function off at 0, using a piecewise function of the original:


Which when I print, looks somewhat about right:

Sorry it's so hard to see but you get the idea. The problem is that this seems to set the whole function to 0, rather than just the bits that should clip:


The piecwise function seems to be evaluating the fN>0 condition to true for all input values p,t, rather than substituing the new input values into the original function fN, and then evaluating the condition for every point, not really sure what the problem is, would appreciate some help!

Calculateif 

Determine which of the limits exist and calculate 
if 

Find the intersection points of the curves and build graphics. 
P.S. Sorry for the spam questions on the forum, but I need to pass the work as soon as possible.

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