How come does "residualQQplot" give me a strange ...

Hello :)

I have a math problem, where I first need to use Linear regression to find the equation based on a set of data. I did that, no problem.

However, in the next part of the problem I need to check if the residuals are under "normal distribution". Usually, I check if a dataset is normally distributed via "QQ-plot", and there will be no problems. But this time, because I need to check the residuals, I need to use the "residualQQplot(data,LinReg)" command to make it happen. But when I read the mean-value, mu, it says "-0," and nothing else? I know it should be "-3,2752*10^-15.

The standard deviation is correct.

How do I fix this, so the residualQQplot shows me the right result?

I have attached the worksheet here. worksheet_-_linear_reg_and_residuals_for_normal_distribution.mw

Thank you!

Maple gives solutions may have been lost unless tw...

I can't understand this behavior. Any idea why it happens?

Solve is able to solve equation   f(y)=x+A for y, but can't solve   f(y)=x for y.

This is unexpected for me. I do not see why it can solve it when RHS is x+A but not when RHS is just x.

 > interface(version);

 > Physics:-Version();

 > restart;

 > sol:=int(1/sqrt(sin(y)),y); solve(sol=x,y)

Warning, solutions may have been lost

 > sol:=int(1/sqrt(sin(y)),y); solve(sol=x+b,y): {%}; #to eliminate duplicates

 >

I can trick it to solve  f(y)=x for y  by asking it to solve f(y)=x+A for y and then set A=0 in the solution. But one should not have to do this. Is this a bug or Am I missing something?

Unit confusion due to "different" joules...

Hello.

I am very new to Maple. Many this are great, but I do not understand how maple deals with, especially, radiological units. In particular regarding joules [J] wich Maple seems to have alt least three types:

1) J - in relation to work

2) J(radiation) in relation to Gy (Gray) J/kg

3) J(dose_equivalent_index) in relation to Sv also J/kg

Why does Maple distinguish between these "joules"? As a phycisist they are all (well maby not entirely for Sv) equal to me. How can I make Maple treat them all at the "same joule"?

I have tried the following first:

with(Units[Standard]) and

with(Units[Natural])

Best,

Carsten

Wrong `coulditbe`?...

If I understand correctly, both of

```int(RETURN(is(y::positive)), y = 0 .. x) assuming 0 <= x, x < 1;
int(RETURN(coulditbe(y = 1)), y = 0 .. x) assuming 0 < x, x < 1;```

should output . However, Maple simply returns  for the second one.
Isn't this result incorrect? Or am I missing something?

Filter out non-isomorphic graphs by canonical labe...

I would like to remove isomorphs from some graphs. That is to filter out non-isomorphic graphs.

```graph_list := [GraphTheory:-CompleteGraph(3), GraphTheory:-PathGraph(3),Graph({{a,b},{b,c},{c,a}})]:

# Create a table to store non-isomorphic graphs
non_isomorphic_graphs := table():

# Counter for indexing the table
counter := 1:

# Iterate over each graph and check if it is isomorphic to any of the stored graphs
for g in graph_list do
is_isomorphic := false:
for key in indices(non_isomorphic_graphs,'nolist') do
if GraphTheory:-IsIsomorphic(g, non_isomorphic_graphs[key]) then
is_isomorphic := true:
break:
end if:
end do:
if not is_isomorphic then
non_isomorphic_graphs[counter] := g:
counter := counter + 1:
end if:
end do:
op(non_isomorphic_graphs)
DrawGraph~(non_isomorphic_graphs,  layoutoptions = [neutral_color = "pink", initial = spring])
```

A canonical form is a labeled graph Canon(G) that is isomorphic to G, such that every graph that is isomorphic to G has the same canonical form as G. I noticed that Maple has a function called CanonicalGraph. Can this function achieve the effect I want? I can easily achieve this by combining the  canonical form and property of sets  in  Sage.

```graph_list = [Graph([(0, "a"), ("a", 2), (2, 0)]),graphs.PathGraph(3), graphs.CompleteGraph(3)]
non_isomorphic_graphs_labels = {g.canonical_label().copy(immutable=True) for g in graph_list}```

An underlying motivation：My collaborators and I designed generation rules (algorithms) for 1-planar 4-trees；see https://arxiv.org/abs/2404.15663. Since the generating process is based on 1-planar embeddings, it will ultimately require filtering non-isomorphic graphs among a list of embeddings. I would be especially delighted to see that someone implement our algorithm in the future. Currently, I am stuck on handling some labeling details. It is somewhat similar to generating Apollonian networks (planar 3-trees). However, since its simplicial vertices are only two, the growth rate will not be too fast as the number of vertices increases.

How to Control the Display of an Object in a Maple...

Can the display of an object o in Maple, i.e.
> o;
display of the object
be controlled in a standard Maple worksheet, e.g. with Typesetting or something similar?

Error in DEtools/DEplot/CheckDE - Derivatives must...

Hello,

I have come across a problem in Maple, when I try plotting af slope field from my differential equation.

I have tried different ways of defining the ODE, but when I use it in the command of "linjeelementer" (Danish for line elements - It's a command that's part of a package called "With (Gym)" in Maple, it gives me the error: Error, (in DEtools/DEplot/CheckDE) - Derivatives must be given explicitly.

I don't understand what derivatives I must "give explicitly"?

Translation of the relevant sentences if anyone needs it when looking at the screenshot:

"I need to draw a slope field for the differential equation along with the solution curve for the population growth in India after 1960.

I define the differential equation:
ODE := -0.000032229*y^2 + 0.065843*y - 15.103"

"I am drawing the slope field for the differential equation along with the solution curve for the population growth in India after 1960, i.e., the solution curve that passes through the point (0,449):I am drawing a slope field for the differential equation along with the solution curve for the population growth in India after 1960, i.e., the solution curve that passes through the point (0,449):
linjeelementer(ODE, y(t), t = 0 .. 350, y = 0 .. 2000)"

warning (`rtable_alias`)...

Hi,

I'm trying out the 2024 version of Maple and I'm getting the following warning message:

Warning, not a built-in function (`rtable_alias`)

which I didn´t get for the 2023 version. I have no clue where it is coming from since it happens even when I start a new worksheet:

I've also attached print outs of the same worksheets (from Maple help examples and from Maple Portal), one using Maple 2023 version and the other one using Maple 2024 version so youcould see the warning and some other problems.

I really appreciate if someone would have an idea of what is going on here. Thanks very much in advance.

interpolation_2023.pdf

interpolation_2024.pdf

optimization_2023.pdf

optimization_2024.pdf

Why does maple not add minutes to hours?...

This is perhaps a stupid question. It is quite easy to add a vector with minutes to 60 minutes. However, when I try to do this stating 1 hour instead of 60 minutes it does no longer do the calculation. Why is this? Thank you for any explanation.

QuestionMP.mw

Command extension: Why is simplify(...,ext) not wo...

In the example below, the second call to simplify is ineffective

```eq := (a*x + b)/(c*x + d) = 1;

`simplify/nodenom`:= x -> (numer@(lhs - rhs) = 0)(x);

`simplify/nodenom`(eq);
simplify(eq, nodenom);```

Why is that?
Convert, for example, works

````convert/nodenom`:= x -> (numer@(lhs - rhs) = 0)(x);

`convert/nodenom`(eq);

convert(eq, nodenom);```

How can I solve a set of linear differential equat...

Deal All,

I have a system of linear differential equations with unknown functions T[1](t) to T[n](t). In the attached example, I considered the value of n equal to 10, but depending on the problem, the value of n may be higher. Maple is not able to solve this problem analytically with the ‘dsolve’.

Does anyone have an idea to analytically solve for such a set of linear differential equations?

Best wishes

Set_of_Linear_DEs.mw

Triple integral doesn't work...

I try to solve triple integraton in Maple with this code.

r := a + (b - a)*z/h;
x1 := sqrt(r^2 - y^2);
V := int(int(int(1, x = -x1 .. x1), y = -r .. r), z = 0 .. h);

but it leaves the last integral dz in the answer and warns: unable to determine if a*h/(-b+a) is between 0 and h; try to use assumptions or use the AllSolutions option
What is the problem?
and i need to get V = Pi*h(a^2 + ab +b^2)/3

Regards

Maple solve hangs depending on what letters are us...

Could someone help me understand why Maple hangs solving these two equations when the names of unknowns is c__1,c__2   or the old _C1, _C2?

This worksheets shows this. I had to put timelimit of 90 seconds, else it hangs may be forever.

This example came from looking at why Maple seems to hang randomly when I run the same problem. I still do not know why, but is seems to have something to do with the use of  lower case c__1 or _C1.

 > interface(version);

 > Physics:-Version();

 > restart;
 > dsolve(diff(y(x),x\$9)=1,arbitraryconstants=subscripted);

 > eqs:=[-1/2*arctanh(1/2*sqrt(1 + 2*c__1)*sqrt(2)/sqrt(c__1))*sqrt(2)/sqrt(c__1) = c__2, 1 = (-exp(2*c__2*sqrt(c__1)*sqrt(2)) + 1)*sqrt(c__1)*sqrt(2)/(exp(2*c__2*sqrt(c__1)*sqrt(2)) + 1)]; unknowns:=[c__1,c__2]; time(); C_sol:=[timelimit(90,solve(eqs,unknowns))]; time()

Error, (in evalf/hypergeom) time expired

 > restart; #try again but do not do the arbitraryconstants=subscripted now.
 > eqs:=[-1/2*arctanh(1/2*sqrt(1 + 2*c__1)*sqrt(2)/sqrt(c__1))*sqrt(2)/sqrt(c__1) = c__2, 1 = (-exp(2*c__2*sqrt(c__1)*sqrt(2)) + 1)*sqrt(c__1)*sqrt(2)/(exp(2*c__2*sqrt(c__1)*sqrt(2)) + 1)]; unknowns:=[c__1,c__2]; time(); C_sol:=[timelimit(90,solve(eqs,unknowns))]; time()

 > #see? it finisghed instantly now.

The same thing happens If I use the old _C1 and _C2 instead of c__1 and c__2. It also hangs.

The following worksheet shows this.  If I change _C1 and _C2 to other symbols, say C1 and C2, then it does not hang.

Why the names of the unknowns makes difference to solve?

 > restart;

 > eqs:=[-1/2*arctanh(1/2*sqrt(1 + 2*_C1)*sqrt(2)/sqrt(_C1))*sqrt(2)/sqrt(_C1) = _C2, 1 = (-exp(2*_C2*sqrt(_C1)*sqrt(2)) + 1)*sqrt(_C1)*sqrt(2)/(exp(2*_C2*sqrt(_C1)*sqrt(2)) + 1)]; unknowns:=[_C1,_C2]; time(); C_sol:=[timelimit(90,solve(eqs,unknowns))]; time()

Error, (in evalf/cos) time expired

 > restart;

 > eqs:=[-1/2*arctanh(1/2*sqrt(1 + 2*C1)*sqrt(2)/sqrt(C1))*sqrt(2)/sqrt(C1) = C2, 1 = (-exp(2*C2*sqrt(C1)*sqrt(2)) + 1)*sqrt(C1)*sqrt(2)/(exp(2*C2*sqrt(C1)*sqrt(2)) + 1)]; unknowns:=[C1,C2]; time(); C_sol:=[timelimit(90,solve(eqs,unknowns))]; time()

Only thing I see in help related to name of symbols to solve for is this:

The solve command solves one or more equations or inequalities for the specified unknowns. The unknowns may be names, including indexed names (though for efficiency reasons, indexed names should be avoided when possible),

ps. This looks like a bug to me. So I send bug report to Maplesoft support also.

pps. I tried this in Maple 2023 and Maple 2022 and same behavior. Could someone with earlier version of Maple try to see if this behavior was there also?   It can possibly be correct that the choice of letter used makes difference for solving equations. I have to use c__1 and c__2 etc.. since these equations come from differential equations and this is what I use for constants of integrations., Otherwise I have to make lots of changes now to use different letters.

Update

did trace on solve using _C1 and _C2 and then using A,B for variables to solve for. Code flow is different. This expalins why it hangs. The flow starts the same until it gets to

TriangularDecomposition: something went wrong during backsubstitution - trying a different variable order

Then when using _C1 and _C2 the code goes into different path than when using A,B.

Here is flow when using _C1,_C2.

```eqs:=[-1/2*arctanh(1/2*sqrt(1 + 2*_C1)*sqrt(2)/sqrt(_C1))*sqrt(2)/sqrt(_C1) = _C2, 1 = (-exp(2*_C2*sqrt(_C1)*sqrt(2)) + 1)*sqrt(_C1)*sqrt(2)/(exp(2*_C2*sqrt(_C1)*sqrt(2)) + 1)];
unknowns:={_C1,_C2};
time();
infolevel[solve]:=5;
C_sol:=[timelimit(60,solve(eqs,unknowns))];
time()

Main: Entering solver with 2 equations in 2 variables
Main: attempting to solve as a linear system
Recurse: recursively solving 2 equations and 2 inequations in 2 variables
Transformer:   solving for linear equation in _X000001
Recurse: recursively solving 2 equations and 2 inequations in 2 variables
Recurse: recursively solving 3 equations and 2 inequations in 3 variables
Dispatch: dispatching to Exponentials handler
Transformer:   solving for linear equation in _S000004
Recurse: recursively solving 3 equations and 3 inequations in 4 variables
Dispatch: dispatching to Rename handler
Dispatch: renaming _S000005 = arctanh(1/2*_S000002*RootOf(_Z^2-2,index = 1)/_S000001)
Recurse: recursively solving 3 equations and 3 inequations in 5 variables
Dispatch: handling polynomials of the form a*x^n-b
Dispatch: dispatching to PolynomialSystem handler
Main: polynomial system split into 1 parts under preprocessing
Main: using RegularChains based methods
SolverVariableOrder: using the variable order  _S000003 > _X000002 > _S000005 > _S000002 > _S000001
TriangularDecomposition: using deterministic algorithm for decomposition
TriangularDecomposition: decomposition successfully found 1 components
TriangularDecomposition: backsubstituting to form solutions
TriangularDecomposition: something went wrong during backsubstitution - trying a different variable order
Transformer:   solving the uncoupled linear subsystem in {_S000003, _X000002}
Linear: solving 2 linear equations
Polynomial: # of equations is: 2
Polynomial: best equation / unknown _S000005*_z1 _X000002 2*_S000001
Polynomial: # of equations is: 1
Polynomial: best equation / unknown -_z1*_S000001+1 _S000003 _z1*_S000001+1
Polynomial: backsubstitution at: 2
Polynomial: backsubstitution at: 1
Main: polynomial system split into 1 parts under preprocessing
Main: subsystem is essentially univariate
UnivariateHandler: subsystem has only one equation
UnivariateHandler: solving as if univariate in _S000002
Recurse: recursively solving 1 equations and 0 inequations in 1 variables
Dispatch: dispatching to OnlyIn handler
Transformer:   solving for linear equation in _S000006
Recurse: recursively solving 1 equations and 0 inequations in 1 variables
Transformer:   solving the uncoupled linear subsystem in _S000006
Recurse: recursively solving 1 equations and 1 inequations in 1 variables
Transformer:   solving the uncoupled linear subsystem in t
Error, (in evalf/hypergeom) time expired
```

This is trace when using A,B

```eqs:=[-1/2*arctanh(1/2*sqrt(1 + 2*A)*sqrt(2)/sqrt(A))*sqrt(2)/sqrt(A) =B, 1 = (-exp(2*B*sqrt(A)*sqrt(2)) + 1)*sqrt(A)*sqrt(2)/(exp(2*B*sqrt(A)*sqrt(2)) + 1)];
unknowns:={A,B};
time();
infolevel[solve]:=5;
C_sol:=[timelimit(90,solve(eqs,unknowns))];
time()

Main: Entering solver with 2 equations in 2 variables
Main: attempting to solve as a linear system
Recurse: recursively solving 2 equations and 2 inequations in 2 variables
Transformer:   solving for linear equation in A
Recurse: recursively solving 2 equations and 2 inequations in 2 variables
Recurse: recursively solving 3 equations and 2 inequations in 3 variables
Dispatch: dispatching to Exponentials handler
Transformer:   solving for linear equation in _S000004
Recurse: recursively solving 3 equations and 3 inequations in 4 variables
Dispatch: dispatching to Rename handler
Dispatch: renaming _S000005 = arctanh(1/2*_S000002*RootOf(_Z^2-2,index = 1)/_S000001)
Recurse: recursively solving 3 equations and 3 inequations in 5 variables
Dispatch: handling polynomials of the form a*x^n-b
Dispatch: dispatching to PolynomialSystem handler
Main: polynomial system split into 1 parts under preprocessing
Main: using RegularChains based methods
SolverVariableOrder: using the variable order  _S000003 > B > _S000005 > _S000002 > _S000001
TriangularDecomposition: using deterministic algorithm for decomposition
TriangularDecomposition: decomposition successfully found 1 components
TriangularDecomposition: backsubstituting to form solutions
TriangularDecomposition: something went wrong during backsubstitution - trying a different variable order
Main: polynomial system split into 1 parts under preprocessing
Main: applying the solver for domain=absolute, engine=traditional
PseudoResultant: 225530 [1 200002087 _S000001] 3 3 151 2 45 0
PseudoResultant: 120059 [2 200004772 _S000003] 2 2 131 0 3 0
PseudoResultant: 134507 [1 700002396 _S000002] 1 1 53 0 3 0
PseudoResultant: -10 [] 0 0 3 0 3 0
PseudoResultant: 1 solutions found, now doing backsubstitution
PseudoResultant: backsubstitution of _S000002
PseudoResultant: backsubstitution of _S000003
PseudoResultant: backsubstitution of _S000001
SolutionsLost: setting solutions lost flag
Main: solving successful - now forming solutions
Main: Exiting solver returning 0 solutions

solve: Warning: no solutions found```

File open not working on Windows system...

This is new:

Maple 2024 frozen on opening recent files

Maple 2023 frozen on opening

Maple 2022 frozen on opening start page

Maple 2020 opening start page

The above system state is constant for about 30 min. Maple sessions without start page are working. I can enter code but file opeing and saving does not work. The fact that Maple 2020 is also not working makes it unlikely that the Java environement is part of the problem.

I have several times restarted the system. The rest of the system is working.

Something happened to the system and I have no clue what is was and what I can do about it.

Any ideas or suggestions what I could try? Windows 10.

ODEs:-ODESteps gives error on first order linear o...

Why Maple gives this error on solving first order linear ode using ODESteps?

 > interface(version);

 > Physics:-Version();

 > ode:=diff(y(x),x)+x*y(x)=1; ic:=y(0)=0; dsolve([ode,ic]);

 > Student:-ODEs:-ODESteps([ode,ic])

Error, (in Student:-ODEs:-OdeSolveOrder1) invalid input: too many and/or wrong type of arguments passed to solve; first unused argument is _C1