singular(ln(y^2+1),y);

        {y = -I}, {y = I}, {y = infinity}, {y = -infinity}.

But if "y" was real, then there are no finite singularities, since y^2 is always positive and hence y^2+1>0 always. Adding assumptions did not help

singular(ln(y^2+1),y) assuming y::real;

gives same result. RealDomain does not support singular.  But I am no longer using RealDomain as it seems bugy.

I know I could filter out these complex results using remove(), but it would be nice if there was a way to singular supports assumptions. Is there a way to do it?

Why are the following 2 commands produce different result?

restart;
RealDomain:-solve({y=y,y<>0},y);
solve({y=y,y<>0},y);

                            [y = 0]
                            {y <> 0}
 

Should not the result be the same?

solve({y=y,y<>0},y) assuming y::real;
                           {y <> 0}

Maple 2018.1. 

Dear friends,

I noticed that the function numbcomb from the package combinat fails to calculate a value properly.

Let's try to calculate the example from the function's help page:

combinat[numbcomb](7, 3);
combinat[numbcomb](5, 4);

returns 35, 5 correspondingly, whereas should be 15 and 4.

Please, check this in your systems. Maybe, this is a bag in my installation?

Suppose I have a subset of R^2, say (x,y) € [0,1] x [0,1]

Now I map

x=r*exp(t)

y=r*exp(-t)

Is it possible to do a 2d contourplot to just see where [0,1]x[0,1] is mapped onto ?

Hi everyone,

I'm having some difficulty replicating a vector diagram. 

So I have learnt how to plot the vector diagram and I have been getting the correct results however the graph I am trying to replicate has some sort of limit within the range they are using which changes the direction of the vector. I was hoping to get this result, but I don't know how to achieve it. Could anyone point me to the right direction please.

Graph I want to replicate (i've highlighted the section that I want to achieve), what I get.

I look forward to your replies.

Thank you in advance

Are these errors to be expected? Why do they happen?

restart;
solve({x<>10, -infinity<x , x<infinity, -infinity<y , y<infinity},{x,y});

Error, (in solver) invalid input: SolveTools:-Inequality:-LinearUnivariateSystem expects its 1st argument, eqns, to be of type ({list, set})({`<`, `<=`, `=`}), but received {x <> -infinity, x < 10}

But it works when replacing x<>10 by y<>10

restart;
solve({y<>10,-infinity<x , x<infinity, -infinity<y , y<infinity},{x,y});
            {10 < y, x < infinity, y < infinity, -infinity < x}, {y <> -infinity, x < infinity, y < 10, -infinity < x}

What is the difference in the above two?

It also work when replacing x<>10 by x=10

solve({x=10, -infinity<x, x<infinity, -infinity<y , y<infinity},{x,y});
               {x = 10, y < infinity, -infinity < y}

It also works when removing the y parts by keeping x<>10

solve({x<>10, -infinity<x , x<infinity},{x,y});
           {y = y, 10 < x, x < infinity}, {y = y, x < 10, -infinity < x}

it also works when removing x<>10 and putting back the y stuff

solve({-infinity<x , x<infinity, -infinity<y , y<infinity},{x,y});
              {x < infinity, y < infinity, -infinity < x, -infinity < y}

Why Maple gives an error for some cases and not the others?

Maple 2018.1

Hi

I need to find a relation between delta [m,k] in terms of m and k

delta[m,k]=f(m,k), where k=0,1,2,...,m

A code is written (delta.mw) to find delta[m,k] for a certain amoun of m.

Is there a way or a code to find a general form of f(m,k)?

Thanks

Hello

I've written a completely symbolic expression involving sum function. When I hit enter, Maple 2016.2 evaluates the expression although it's completely symbolic and not evaluable.

How to stop Maple from falsely evaluating a symbolic expression? I dis use the restart command to make sure all variables are empty. When evaluating Maple generate a very large open form expression that makes no mathematical sense.

Maple file in the following link

https://www.dropbox.com/s/13ciwothh1pqijk/sumBug.mw?dl=0

Please advice

Thanks

I am fairly new to Maple and I'm currently researching twisted multiloop algebras. I'm trying to use Maple to automate many of the calculations. For example, suppose xy = yx + 2z and I have the expression wxy (the variables are non-commutative. I already have this functionality working properly with the physics package). I want Maple to make the substitution for xy and simplfiy. For example: wxy = w(yx + 2z) = wyx + 2wz. Is this possible?

Thank you for your help.

I have two matrices, one of the dimension of solution space that i have been using solve to navigate
this matrix will look something like:

M := matrix([[3, 2, 1], [2, 1, 1],[2, 1, 1]])

and I have another matix of the times that it takes solve to find these regions:

N := matrix([[.2, .4, .8], [.3, .6, .5], [.8, 2.3, 2.6]])

I'd like to find the sets {N[ij]:M[ij]=m for some integer m}; that is I'd like to get all the elements of N on entries of M with the same number so i can start thinking about them statistiaclly.

i.e. for 3 i'd like the list [.2]

      for 2                      [.4 .3 .8]

and so on.
 

I wish to extract a minimum route in a network given both start and end positions.

Also, I wish to avoid a spur in the circuit and obtain one continuous orthogonal  path. 

As an example, take the 7-node case having 14 arcs (see worksheet) using Dijkstra's algorithm (I assume this is fit for purpose in this particular case).

Starting with node 1, the algorithm suggests the paths:

1>2>3>4>5>6>7.>8>9 and 1>2>3>4>5>10>11>12>13>14 (here, there is a spur at node 5 where the paths separate)

Is it possible obtain one minimum path?

The source node is prescribed in the routine - can anyone explain how to prescribe the end node?

Thanks for reading!

Shortest_Circuit.mw

I tried to integrate

int((1-x^floor(u))/((1-x)*u^2), u = 1 .. infinity, numeric)

where x=-1. The result should be log 2 = 0.6931471806. However it gives me 0.6687714032.

When using a numeric cut off, the result improves, so what is the issue here?

6687714032

Hello.

I have this problem when executing the entire worksheet or selected groups.
Also Maple can crash by itself, to its heart's content)
What I can do to solve this problem?
OS: W7 x64, Java is up to date

Thx.

Hi Guys i need some Help. 

I created a work sheet where i am calculatin the polynominial coefficient of an equation. The Problem is that if i take these coefficient and then calculate the root with Matlab and compare it with the symbolic toolbox  i get wrong roots. My question now is did i something wrong by creating the coefficient ? 

Polynom_Calculation.mw 

These are the values for the parameters : 

b1=0
b2=0
v1=0
v2=0
s1=0
s2=0.175
j2=0.28
tau =20
th1 = 0
th3 = 0
 

i added  my Maple skript. i hope that sb can help me.

In the first one I used hypergeometric function where the number is converged. Now using the series expansion of hypergeometric function I rewrite the equation as in the 2nd and 3rd case. But here it is not converging. I expect the same answer as in the first case i.e 0.14042. Thank you

problem2.mw