Hello community,

how can I import only selected columns from a csv file?
My current code is the following:

IK := Import("Indifferenzkurve.csv", output = datadir)

However, I'd like to only import the three columns "E","T", and "S_P and S_TEV", not column " " and "Diff".
On this basis, I'd like to plot "S_P and S_TEV":

plot3d([IK], E = 0.1 .. 1000000, T = 1 .. 45)

Thanks so much in advance!
Rebekka

Hello,

I noted that add and 'add' can give different result, can somebody help me understand it?  Consider the code below:

>phi1 := GAMMA(-(1/2)*vst-8.333500000-(1/2)*r)*GAMMA((1/2)*vst+21/2+(1/2)*r); phi2 := GAMMA(16.66700000+r-2*vst)*GAMMA(2.166500000+vst); xi1 := -vst; xi2 := 16.66700000+r-2*vst; z := 37.52950222; K := 9.846618489*10^(-38)*33.330^(.5000000000*r+10.)

### Then I have the following sums (they were supposed to give the same results):

>f := unapply(K*add(phi1*(-1)^vst*z^(-xi1)/factorial(vst)+phi2*(-1)^vst*z^(-xi2)/(.5*factorial(vst)), vst = 0 .. 10000), r):

>g := unapply(K*'add'(phi1*(-1)^vst*z^(-xi1)/factorial(vst)+phi2*(-1)^vst*z^(-xi2)/(.5*factorial(vst)), vst = 0 .. upto), [r, upto]);

# I am interested in the following quantities:

>evalf(f(1)/f(0));

-6.265883733

>evalf(g(1,10000)/g(0,10000))

25.80438437

That seems very strange to me, why maple gives different results?

How we can locate legend inside the plot like the one in the picture

Thank you!

I want to calculate the arithmetic average of a class of 5 students for 3 different exams. I want to calculate a different average for each exam. I want to use i and j variables. exam grades will be random like 20*i. How can i do this program? Any can do this? Thank you 

I try this program but i get error

total:=0;

numb:=0;

for i from 1 to 3 do

for j from 1 to 5 do

N[i,j]:=20*i;

total:=total+N[i,j];

numb:=numb+i

end do;

end do;

evalf(total/numb);

The date, month, year  22/02/2022 is said a beautiful numbers. Because, the number 2202 symmetry to the number 2022. How can I find another beautiful numbers like that ?

I have two surfaces f=f(x,y) and g=g(x,y), is there any way to find the equation of intersection curve of them in maple?

contact.mw

hello i want to solve this pde equation numericaly with pdsolve:

diff(u(x, t), x, x) + diff(u(x, t), t, t)/0.5^2 - 2*diff(u(x, t), x, t)/0.5^2 = -0.0013*u(x, t) + 8.6510*u(x, t)^3

and enter this codes:

PDE := diff(u(x, t), x, x) + diff(u(x, t), t, t)/0.5^2 - 2*diff(u(x, t), x, t)/0.5^2 = -0.0013*u(x, t) + 8.6510*u(x, t)^3
IBC := {u(0, t) = 0.01, u(4, t) = 0, u(x, 0) = 0, D[1](u)(x, 0) = 0};
pds := pdsolve(PDE, IBC, numeric, t = time, rage = 0 .. 1);

but this error appear :

Error, (in pdsolve/numeric/process_IBCs) initial/boundary conditions can only contain derivatives which are normal to the boundary, got (D[1](u))(x, 0)

and i don't know how ti fix it.

can someone help me?

how to transform this program using LinearAlgebra instead of linalg  ?

restart;
with(plots);
unprotect(gamma, D);
interface(rtablesize = 10): _EnvHorizontalName := 'x': _EnvVerticalName := 'y':
f := (x, y) -> 4*x^2 + 4*y*x + y^2 - 8*x + 16*y - 17: (for instance)
NULL;
Fg := proc(P::polynom, v::set, V::list, N::list) 
local C, M, i, j; 
C := coeffs(f(x, y), v, M); seq(`if`(member(op(i, [M]), N, 'j'), op(j, V) = op(i, [C]), NULL), i = 1 .. nops([M])); end proc:
Fg(f(x, y), {x, y}, [A, B, C, D, E, F], [x^2, y*x, y^2, x, y, 1]):
assign(%);
Delta := -4*A*C + B^2:
var := [x, y]:
with(linalg):
AA := matrix([seq([seq(diff(f(x, y), var[i], var[j])/2, j = 1 .. 2)], i = 1 .. 2)]):
vp := sort([eigenvals(AA)]):
print(`Valeur propres de AA ` = vp):
DD := jordan(AA, 'P11'):
print(`Matrice diagonale semblable à AA:   DD` = evalm(DD)):
G := map(normalize, GramSchmidt([col(P11, 1 .. 2)])):
PP := map(simplify, concat(op(G))):
print(`Matrice de passage orthogonale:   PP` = evalm(PP)):
print(`Directions principales de la conique:`):
print(`I1 ` = col(PP, 1), ` J ` = col(PP, 2)):
alpha := 1/2*arctan(B/(A - C)):
print('alpha' = evalf(%)):                 

M1 := matrix(1, 2, [X, Y]):
M2 := matrix(2, 1, [X, Y]):
multiply(M1, AA, M2):
N := matrix(1, 2, [D, E]):
multiply(M1, AA, M2) + multiply(N, M2):
multiply(M1, transpose(PP), AA, PP, M2) + multiply(N, PP, M2):

NULL;
The parabola in the new base is Y`^2 =X*(8*sqrt(5))/5 , <sqrt(5), -2*sqrt(5)>, <sqrt(5), 2*sqrt(5)>

I am trying to define a sum which is obtained from linked functions (which also contain the sum command). 

The problem is: if I modify the first function p and rerun the worksheet (except fot the restart command), then the changes do not affect the result. Does anyone know why? Thank you very much.
 

Download problem_with_sums.mw

I am working with the de Sitter metric which takes the form 

$$g=\tau^{-2}\left(-\left(\Lambda / 3-\tau^{2}\right)^{-1} d \tau^{2}+\left(\Lambda / 3-\tau^{2}\right) d t^{2}+g_{\mathbb{S}^{2}}\right)$$

or 

g := evalDG((-`dτ` &t `dτ`/(Lambda/3 - tau^2) + (Lambda/3 - tau^2)*(dt &t dt) + (dtheta &t dtheta) + sin(theta)^2*(dphi &t dphi))/tau^2)

in the co-ordinates $\{\tau, t, \theta, \phi\}.$

or 

DGsetup([tau, t, theta, phi], M1, verbose)

Define

F := evalDG(-Q*(`dτ` &t dt) + Q*(dt &t `dτ`))

Then I want to define the following function which takes a two tensor (metric) and returns a two tensor as well. 

Here \dot(g) is the input tensor, F is the two tensor defined above and the g is the de Sitter metric. 

I want to evaluate this expression of \dot{g} = d tau^2/tau^2 and other metrics. How can I do this in Maple?

Any help will be much appreciated.

With Maple, is there a way to quickly solve systems of equations where the solutions are the coordinates of a vector?
An example of an idea: A problem to solve:
There are points: M(1,0,0) and N(0,0-1); plane (Q): x-y-4=0. Determine the plane (P) containing M and N, making with (Q) a 45 degree angle.
Solution:
Assume: Equation of (P): Ax+By+Cz+D=0
We have:
Normal vector of (P): np(vector):=<A,B,C>
Normal vector of (Q): nq(vector):=<1,-1,0>
Direction vector of line NM: dNM(vector):=<1,0,1>
To determine: A, B, C, it is necessary to solve the system of equations:
cos(45 degrees)= np(vector).nq(vector)/abs(np(vector)) x abs(nq(vector))=1/Sqrt(2)
  dNM(vector).np(vector)=0....

Hi !

I want to solve several summations which at first glance seems very easy to me.

But I definitely hit a wall. I have Maple 2018 on Windows 10.

I'm not very familiar with the sumtools or Sumtools packages.

 I have attached a file that gives you an example summation and the

 solution I found and especially I show you the way that I obtained this solution.

  The big question is:

  Is there a way to transform this summation to arrive at my solution?

  Or . Can the result I obtained be demonstrated?

  Maple seems unable to solve this summation. Mathematica did no better.

  I know very well that this is more a question for mathematicians than for

Maple users. But when I look at the questions in Mapleprimes I see

although there are good mathematicians behind most of these questions.

Thank you in advance ! 

sum1.mw

hi 

hiiiiiiiiiii

i am working and modling on brushless motor for my project but when i run that i get this error and i can not fix that could you please help me. error is :

equation generation

(}),At offset 4370 in `:-2108.m`, unexpected DAG type: 0,125

every project  i run  has the same error 

Hi everyone...

How can I plot the below function: 

x^2+(y-x^(2/3))^2 = 1;

tnx...

Resistor grid of one ohm to make rubik cube of 3*4*5.
Resistance of red node to node is 

nx, ny, nz;

Ans := R3D;
Ans*Unit('ohm');
                            3, 4, 5

               1.211 Unit(&Omega;)

Tokoro.

grid cube electrical-engineering