I have a system of six ODEs. i solve them numerically using dolve,numeric command. the problem is setting step size for example stepsize=1e-5 or minstep=500 lead to a result of order 1e-2; But without using this option, results are of order integer numbers. could any one help? tnx in advance

EDITED
 

Download ode_problem.mw

Hello,

I'm trying to fit experimental data to a model in which a variable is the result of an equation.

In a procedure I solved the equation and found lambda22 for each of the data lambda11 I have. It depends on a a parameter I need to identify to fit the data to the model.

But then when I use DataFit from DirectSearch package, I get this error :

Is it impossible to specify more than one independant variable ? Or is it a problem coming from the procedure ?

Thanks in advance,

Manon

data.xlsx

restart;

data:=ExcelTools:-Import("D:/data.xlsx") : # importer les donnees
with(LinearAlgebra): 
lambdaX:=Column(data,1): 
PK1X:=Column(data,2):


tensF:=Matrix([[lambda11,0,0],[0,lambda22,0],[0,0,lambda22]]):
tensFbar:=Matrix([[(lambda11/lambda22)^(2/3),0,0],[0,1/sqrt((lambda11/lambda22)^(2/3)),0],[0,0,1/sqrt((lambda11/lambda22)^(2/3))]]):
tensBbar:=Multiply(tensFbar,Transpose(tensFbar)):

kappa:=100:
tensPK:=Multiply(Transpose(MatrixInverse(tensF)),(2/Determinant(tensF))*a*(tensBbar-(1/3)*Trace(tensBbar)*Matrix(3,shape=identity))+kappa*(Determinant(tensF)-1)*Matrix(3,shape=identity)):
PK1:=tensPK[1,1]:
eq:=0=tensPK[2,2]:


lambda22sol:=proc(aValue) 
   global __old_a;
   local res, i, eq1, sol1, lambda22Est;
   if not [aValue]::list(numeric) then
      return 'procname'(args);
   end if;
   lambda22Est:=Vector(1..RowDimension(lambdaX)):
   eq1:=Array(1..RowDimension(lambdaX)):
   if __old_a<>aValue then
      __old_a:= aValue;
     for i from 1 to RowDimension(lambdaX) do
     	eq1[i]:=eval(eq,[a=aValue,lambda11=lambdaX[i]]):
		sol1:=solve(eq1[i], lambda22);
		lambda22Est[i]:=sol1[1]:
	end do:
	res:=lambda22Est;
   end if;
end proc:

matrix1:=<lambdaX|lambda22sol(0.9)|PK1X>;
DS1:=CodeTools:-Usage(
        DirectSearch:-DataFit(PK1,matrix1,[lambda11,lambda22]));
res2:=eval(PK1,DS1[2]):

Hi,

Using Maple 2020 I can't seem to get a trigonometric equation (fairly simple at that) to solve properly.

solve_err.mw

Here's a capture :

Expected answer is 1/(25*sqrt(3))

Adding +2*Pi on the RHS to match the sign doesn't work either.

Hi everybody, I have a set from fsolve command. As shown in below image

When I want to obtain only numbers, I write cozum[1] but maple gives me c-4=1.591497964.. As you understand I want only numbers. How can I do this? 

int(1/(x-1)+sum((k+1)*x^k,k=0..2018)/sum(x^k,k=0..2019),x);

Direct integration produces a large, messy statement, including numbers like 2017, 2016,...,1

Looking at the parts, the numbers 2020, 2019, etc. are in each.

(**) sum((k+1)*x^k,k=0..2018);
x^2019*(2019*x-2020)/(x-1)^2+1/(x-1)^2

(**) sum(x^k,k=0..2019);
x^2020/(x-1)-1/(x-1)

Looks like this should reduct to some simple expession????

Looking at #6 in http://www.mit.edu/~pax/pdf/qualifying_round_2020_test.pdf

How do I entter the continued fraction in Maple?  I am using the command line interface (actually Emacs).

Hi,

I want to solve a set of equation (four equations) to plot variation of u[i10],u[i20],phi[d0] versus delta[d] for delta[i]=0.5 and different values of alpha (for example, alpha=0, 0.1,0.2)

How can I do that with Maple?

(It should be noted that depending on the sign of phi[d0], one must use Eq. 2a or 2b. The other equations are Eqs. 1,3,4)
I expect to plot figures like the attached figure.

1.zip

I am looking to find a distribution function (both PDF and CDF) for the distance between two points on the unit square.

Each point will be uniformly distributed on the [0,1] interval for both the x and y axes.  The distance between these points (d_ij) will of course be:

d[i, j] := sqrt((x[i] - x[j])^2 + (y[i] - y[j])^2)

I think that using a convolution may be required, but this is over my head.  If anybody can show me (preferably via a Maple worksheet), I would be very appreciative.

Thank you.

As an addition to the post.
Non-orientable surface in the sequence of orientable surfaces. In the picture we see the equations corresponding to the current surface plot.
Just entertainment.
surfaces.mw

Hello,

I have a question about fitting a function to experiemental data. The experimental data is Di = X(zi) +I*Y(zi) for a zi = [z1 z1+dz ...z1+dz*N], where zi are real values. I want to fit a complex function f(z,a,b,c) to the data zi and Di , where a,b,c are complex-valued parameters. Does someone know how to fit a complex function to a complex data? The Maple function that I found work only with real functions and data.

Hello,

I want to define an orthonormal tetrad basis of my choice in a spacetime having a metric given in some system of coordinates. My problem is that Maple automatically proposes an orthonormal metric but this is not the one that suits my requirements. So, I would like to specify the tetrad basis manually. As an example, I am trying to reproduce the calculations in sections 6 and 7 of the article https://arxiv.org/abs/gr-qc/0510083 . Here, the metric $g$ is given by the line element $ds^2 = - (c(t,r)^2 - v(t,r)^2) dt^2 + 2 v(t,r) dr dt + dr^2 + r^2 (d\theta^2 + sin(\theta)^2 d\phi^2)$ in $(t, r, \theta, \phi)$ coordinates. My chosen signature is (- + + +). Let, us adopt the convention used by Maple and denote spacetime indices by Greek alphabets and tetrad indices by lowercase Latin letters. Now, I would like to define a tetrad $e_a = (V, S, \Theta, \Phi)$ (as in section 7 of the article referred to above) where:

V^\mu = \frac{1}{c\sqrt{1-\beta(t,r)^2}}[1, - (v + c \beta), 0, 0] \\

S^\mu = \frac{1}{c\sqrt{1-\beta^2}}[-\beta, c + v \beta, 0, 0] \\

\Theta^\mu = [0,0,1,0]

\Phi^\mu = [0,0,0,1].

Here, $|\beta(t,r)| < 1$. I do not know how I may specify this in my worksheet. This may come of use somewhere later. Now, with this choice of the tetrad, we know that $g(e_a, e_b) = \eta_{ab}$ with $\eta$ being the Minkowski metric in spherical coordinates. After defining this tetrad basis, I finally want to calculate Einstein tensor, components of energy-momentum tensr etc. I have problem with constructing this orthonormal tetrad basis myself. It would be great if you could help me with this.

An additional curiosity: when we work with multiple tetrad bases, is it possible to denote the the tetrad indices by hatted tetrad labels themselves, as in $\eta_{\hat V, \hat \Theta}$?

Thank you.
 

Download dynBH.mw

#include<iostream>
#include<vector>
#include<cmath>
#define NODE 8

using namespace std;
int graph[NODE][NODE] = {
   {0,1,1,0,0,0,0,0},
   {1,0,1,1,1,0,0,0},
   {1,1,0,1,0,1,0,0},
   {0,1,1,0,0,0,0,0},
   {0,1,0,0,0,1,1,1},
   {0,0,1,0,1,0,1,1},
   {0,0,0,0,1,1,0,0},
   {0,0,0,0,1,1,0,0}
};
int tempGraph[NODE][NODE];
int findStartVert() {
   for(int i = 0; i<NODE; i++) {
      int deg = 0;
      for(int j = 0; j<NODE; j++) {
         if(tempGraph[i][j])
            deg++; //increase degree, when connected edge found
      }
      if(deg % 2 != 0) //when degree of vertices are odd
      return i; //i is node with odd degree
   }
   return 0; //when all vertices have even degree, start from 0
}
int dfs(int prev, int start, bool visited[]){
   int count = 1;
   visited[start] = true;
   for(int u = 0; u<NODE; u++){
      if(prev != u){
         if(!visited[u]){
            if(tempGraph[start][u]){
               count += dfs(start, u, visited);
            }
         }
      }
   }
   return count;
}
bool isBridge(int u, int v) {
   int deg = 0;
   for(int i = 0; i<NODE; i++)
      if(tempGraph[v][i])
   deg++;
   if(deg>1) {
      return false; //the edge is not forming bridge
   }
   return true; //edge forming a bridge
}
int edgeCount() {
   int count = 0;
   for(int i = 0; i<NODE; i++)
      for(int j = i; j<NODE; j++)
         if(tempGraph[i][j])
   count++;
   return count;
}
void fleuryAlgorithm(int start) {
   static int edge = edgeCount();
   static int v_count = NODE;
   for(int v = 0; v<NODE; v++) {
      if(tempGraph[start][v]) {
         bool visited[NODE] = {false};
         if(isBridge(start, v)){
            v_count--;
         }
         int cnt = dfs(start, v, visited);
         if(abs(v_count-cnt) <= 2){
            cout << start << "--" << v << " ";
            if(isBridge(v, start)){
               v_count--;
            }
            tempGraph[start][v] = tempGraph[v][start] = 0; //remove edge from graph
            edge--;
            fleuryAlgorithm(v);
         }
      }
   }
}
int main() {
   for(int i = 0; i<NODE; i++) //copy main graph to tempGraph
   for(int j = 0; j<NODE; j++)
      tempGraph[i][j] = graph[i][j];
   cout << "Euler Path Or Circuit: ";
   fleuryAlgorithm(findStartVert());
}

Kind help 

Hi, I generated latex formate of an equation by using a command of maple but when I paste it into MathType, could not get the required equation, can anyone help me

${\frac {1}{51200\, \left( {x}^{2}+2 \right) ^{6}} \left( -187110\,

 \left( {x}^{2}+2 \right) ^{6}\sqrt {2} \left( {Q}^{3}+ \left( {\frac

{18\,k}{11}}-{\frac{18}{11}} \right) {Q}^{2}+ \left( {\frac {320\,{k}^

{2}}{297}}-{\frac {40\,k}{27}}+{\frac{320}{297}} \right) Q+{\frac {80

\,{k}^{3}}{297}}-{\frac {80\,{k}^{2}}{189}}+{\frac {80\,k}{189}}+{

\frac {640\,\lambda}{2079}}-{\frac{80}{297}} \right) \arctan \left( 1/

2\,x\sqrt {2} \right) -93555\, \left( {x}^{2}+2 \right) ^{6}\pi\,

 \left( {Q}^{3}+ \left( {\frac {18\,k}{11}}-{\frac{18}{11}} \right) {Q

}^{2}+ \left( {\frac {320\,{k}^{2}}{297}}-{\frac {40\,k}{27}}+{\frac{

320}{297}} \right) Q+{\frac {80\,{k}^{3}}{297}}-{\frac {80\,{k}^{2}}{

189}}+{\frac {80\,k}{189}}+{\frac {640\,\lambda}{2079}}-{\frac{80}{297

}} \right) \sqrt {2}-374220\, \left(  \left( {Q}^{3}+ \left( {\frac {

18\,k}{11}}-{\frac{18}{11}} \right) {Q}^{2}+ \left( {\frac {320\,{k}^{

2}}{297}}-{\frac {40\,k}{27}}+{\frac{320}{297}} \right) Q+{\frac {80\,

{k}^{3}}{297}}-{\frac {80\,{k}^{2}}{189}}+{\frac {80\,k}{189}}+{\frac

{640\,\lambda}{2079}}-{\frac{80}{297}} \right) {x}^{10}+ \left( {

\frac {34\,{Q}^{3}}{3}}+ \left( {\frac {204\,k}{11}}-{\frac{204}{11}}

 \right) {Q}^{2}+ \left( {\frac {10880\,{k}^{2}}{891}}-{\frac {1360\,k

}{81}}+{\frac{10880}{891}} \right) Q+{\frac {2720\,{k}^{3}}{891}}-{

\frac {2720\,{k}^{2}}{567}}+{\frac {2720\,k}{567}}+{\frac {21760\,

\lambda}{6237}}-{\frac{2720}{891}} \right) {x}^{8}+ \left( {\frac {264

\,{Q}^{3}}{5}}+ \left( {\frac {432\,k}{5}}-{\frac{432}{5}} \right) {Q}

^{2}+ \left( {\frac {512\,{k}^{2}}{9}}-{\frac {704\,k}{9}}+{\frac{512}

{9}} \right) Q+{\frac {128\,{k}^{3}}{9}}-{\frac {1408\,{k}^{2}}{63}}+{

\frac {1408\,k}{63}}+{\frac {97280\,\lambda}{6237}}-{\frac{128}{9}}

 \right) {x}^{6}+ \left( {\frac {4496\,{Q}^{3}}{35}}+ \left( {\frac {

80928\,k}{385}}-{\frac{80928}{385}} \right) {Q}^{2}+ \left( {\frac {

287744\,{k}^{2}}{2079}}-{\frac {35968\,k}{189}}+{\frac{287744}{2079}}

 \right) Q+{\frac {3328\,{k}^{3}}{99}}-{\frac {3328\,{k}^{2}}{63}}+{

\frac {3328\,k}{63}}+{\frac {10240\,\lambda}{297}}-{\frac{3328}{99}}

 \right) {x}^{4}+ \left( {\frac {10672\,{Q}^{3}}{63}}+ \left( {\frac {

21344\,k}{77}}-{\frac{21344}{77}} \right) {Q}^{2}+ \left( {\frac {

1094656\,{k}^{2}}{6237}}-{\frac {136832\,k}{567}}+{\frac{1094656}{6237

}} \right) Q+{\frac {35584\,{k}^{3}}{891}}-{\frac {35584\,{k}^{2}}{567

}}+{\frac {35584\,k}{567}}+{\frac {235520\,\lambda}{6237}}-{\frac{

35584}{891}} \right) {x}^{2}+{\frac {25376\,{Q}^{3}}{231}}+ \left( {

\frac {12352\,k}{77}}-{\frac{12352}{77}} \right) {Q}^{2}+ \left( -{

\frac {7936\,k}{63}}+{\frac {63488\,{k}^{2}}{693}}+{\frac{63488}{693}}

 \right) Q-{\frac{512}{27}}+{\frac {512\,{k}^{3}}{27}}-{\frac {5632\,{

k}^{2}}{189}}+{\frac {102400\,\lambda}{6237}}+{\frac {5632\,k}{189}}

 \right) x \right) }$

Hi,

I am trying to build a procedure to check to see if an nxn matrix is elementary. I am working with the standard definition of an elementary matrix, a square matrix that is formed by performing exactly one row operation on the corresponding identity matrix. It could also be interpreted as a matrix that is exactly one row operation from becoming the identity matrix. Does anyone have any idea how this might be done?

Thanks!

Hello Everyone,

I am currently in the process of building a user interface where a user can input a ply layup for a composite part which needs to be calculated. I want to forbid the use of non-numerical value in the matrix which represents my ply layup, before it gets sent to be calculated, but I am wondering how to check if my matrix has non-numerical values in it. 

At best, it would not only check if the matrix has non-numerical entries, but also give me the indices where exactly that value is present. I have yet been unsuccessful trying to find a fitting command. Do you perhaps know something that might work.
For clairification, allowable entries are in a range of -90 to 90, so it should not look for the "-" in the matrix. 

Best Regards,
Lennart