# MaplePrimes Questions

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## Latest Questions Latest Questions Feed

### How to draw these geometric objects?...

May 12 2016
0 1

Hi, there

How can I draw the excircles, incircles,circumcircle and their centers of a triangle simultaneously with maple13 in a geometric plot? please specify the commands.

M.R.Yegan

### Maximum likelihood estimation...

May 12 2016
1 5

Hi All

Assume that we have a stochastic model with following density function

and our goal is to estimate unknown parameters namely, alpha, beta, landa, mu and sigma by any available method especially maximum likelihood estimation method.
How can we do it with maple software?

Does the "MaximumLikelihoodEstimate" command can help?

or should i define Maximum Likelihood function first and then differentiate it according to unknown parameters?

Ph.D Candidate

Applied Mathematics Department

### Defining custom operator for partial differentiati...

May 11 2016
0 6

 Suppose we have a function can we build a code such that for operator defined as Such that returns where subscripts denote partial derivatives.

Regards

### Can't assign values from a procedure...

May 11 2016
1 5

I defined a procedure, OrderB(0,b,c), that essentially determines the order of a group that is defined by 2 parameters (the first parameter is always zero), so the output is an integer and the procedure is defined for every integer value of both parameters. I wanted to structure the outputs into a matrix with columns that represent one parameter and rows that represent the other. However, whenever I try to apply a method of defining the matrix, Maple returns the values of the procedure and then gives me an empty matrix.

>f:=proc (i, j) -> OrderB(0, i, j+3);
>Matrix(3, f);
1
4
1
1
4
1
1
4
1
[NULL,NULL...]

I tried a second method where I defined a set s such that:

s:={(0,0)=OrderB(0,0,0) , (0,1)=OrderB(0,0,1).....}

but upon execution, maple returns:

1
4
1
....
s:={(0,0)=( ), (0,1)=( )...}

Please Help. I don't know what I'm mising in the code that is keeping Maple from putting the outputs of my procedure into the matrix.

### Error when dsolving...

May 11 2016
1 1

Been working on a diffy q project, new to maple here. Any help is appreciated. Keep getting a similar error.

"Error, (in dsolve/numeric/type_check) insufficient initial/boundary value information for procedure defined problem"

I thought I gave it initial values?

link to screenshot of the error bellow:

http://i.imgur.com/YVE1x7e.jpg

### Maple is unable to evaluate an integral...

May 11 2016
1 5

Hi,

For the paste several years, I have occasionally tested Maple on a simple integral,

simplify(int( exp(-I*k*x)/cosh(x), x=-infinity..infinity) assuming k,real);

The integral is returned unevaluated. There is no problems related to the complex exponential,

since also e.g.

simplify(int( cos(k*x)/cosh(x), x=0..infinity) assuming k,real);

and other variants are not evaluated.

Turning to the inbuilt fourier function (inttrans package) also does not work.

Evaluating laplace(1/cosh(x),x,s), and subsequently substituting s=I*k and s=-I*k and summing WORKS,

but gives (unnecessarily) an ugly result which it cannot simplify.

Finally, subtracting the (manually simplified) correct expression and simplifying gives 0 as

verification. I can not see any technical explanation for this bug.

### A little arithmetical challenge...

May 11 2016
1 1

Hi everybody,

how about a little arithmetical challenge?

known quantities : Z, t, epsilon : reals

let W = X+Y*t    X, Y integers, t real (t with unlimited precision)

let W = Z + epsilon (epsilon < 1/W), Z real (Z with unlimited precision)

W and Z have same decimal expansion ( W - Integerpart[W], Z - IntegerPart[Z] ), up to a certain "rank" (determined by the precision : epsilon)

Y*t and Z have same decimal expansion, up to a certain "rank".

The problem : build an algorithm to find the integer Y, using the "usable" decimal expansion of Z.

### Problem with solving...

May 11 2016
1 4

I am trying to find the root of an equation. The problem is, I keep getting the error

"Error, (in fsolve) Can't handle expressions with typed procedures"

and

Warning, solutions may have been lost

whenever I try to solve it. Anyone have any ideas? My worksheet is here:  1.mw

### Tags associated to data of a pointplot...

May 11 2016
1 8

Hello,

I have some points that i have plotted thanks to the function pointplot.

Is it possible to add tags next the points (like it is possible in Excel) ?

Of course, I have a vector with the definition of the contents of the tags that I would like to add.

Thanks a lot for your help

### Generate matrix form ...

May 11 2016
2 21

Hello,

I cant find solution how to create matrix form from equations of motion. Equations looks like this:

My equations ar much more complicated and one of them looks something like this:

http://i63.tinypic.com/21c5ctk.png

and I want form like this:

I tried to do it using the Generate Matrix but it does not work as I expected. How can you get this form?

### How to convert ODE system to differential form?...

May 11 2016
0 0

how to convert system of differential equations to differential form for evalDG?

[a(t)*(diff(c(t), t))+b(t), a(t)*(diff(b(t), t))+c(t)*(diff(b(t), t)), a(t)*(diff(c(t), t))+a(t)*(diff(b(t), t))+b(t)];

when i try eliminate dt which is the denominator

eliminate([a(t)*dc(t) + b(t)*dt,a(t)*db(t)+dt*c(t)*db(t),a(t)*dc(t)+a(t)*db(t)+b(t)*dt],dt);

[{dt = -a(t)/c(t)}, {a(t)*(c(t)*dc(t)-b(t)), a(t)*(db(t)*c(t)+c(t)*dc(t)-b(t))}]

i got two solutions, which one is correct?

a(t)*(c(t)*dc(t)-b(t)), a(t)*(db(t)*c(t)+c(t)*dc(t)-b(t))

does it mean that two have to use together to form a differential form?

update1

with(DifferentialGeometry):
DGsetup([a,b,c], M);
X := evalDG({a*(c*D_c-b), a*(D_b*c+c*D_c-b(t))});
Flow(X,t);
Flow(X, t, ode = true);

got error when run with above result

### How to solve a variable amount of variables?...

May 10 2016
1 2

Hey all,

The title is probably very poorly explained and doesn't make much sense at all, but here goes nothing:

I define at the start of my .mw file that M:=1, but I need to be able to change it in order to run multiple different iterations.

So what I've come up with so far is a way to get a variable ammount of equations named "eqc(1,3,5,...)" The number of equations I get is equal to the M defined in the beggining. How would I go about solving this?
To give you an idea of something to work with:

So basically I'd need to solve as many of these eqc equations as I get. If I change M to, lets say 30, I'd need to solve 30 equations. This solve option above doesn't work and I've messed around with Vectors and Matrixes but I honesly have no idea what I'm doing there, so I thought best to seek out help.

### Lyapunov exponent...

May 10 2016
1 5

How I can solve this:

for different fn(x0) ? for f(x)=exp(x^2(a-x))

### Simplifying this sum over odd integers...

May 10 2016
1 4

Hey,

I'm trying to make a sum of only odd numbers regarding 2 functions and I've come up with what I assume is a terrible way to do it...

So basically what I want to write is this:

And this should give me something like this:

This works, what I have now. The thing is I need to be able to add and subtract terms in order to compare with other stuff and it just seems so inefficient right now.

### How to unassign local variable in proc?...

May 10 2016
1 8

I want to compute delta but i do not want to show result for delta. i know i need to put
delta := unassign('delta');
but i do not know where to put, i try and error so many times but the answer still the same.
the answer should be in marix form 2x2
[-δD11   0    ]
[0         D22]

>derivation := proc (A, n)
local i, j, k, t, s1, m, D, sols, eqns, BChange, delta; eqns := {}; D := matrix(n, n); BChange := matrix(n, n);
for i to n do
for j to n do
for m to n do
s1 := sum(0*A[i, j, k]*D[m, k], k = 1 .. n)-(sum(A[k, j, m]*D[k, i]+delta*A[i, k, m]*D[k, j], k = 1 .. n));
eqns := union(eqns, {s1})
end do
end do
end do;
sols := [solve(eqns)];
delta := unassign('delta');
t := nops(sols);
for i to t do
for j to n do
for k to n do
BChange[k, j] := subs(sols[i], D[k, j])
end do
end do;
print("BChange:=", BChange)
end do
end proc

> AS1 := array(sparse, 1 .. 2, 1 .. 2, 1 .. 2, [(1, 1, 2) = 1]);
> derivation(AS1, 2);

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