Hello

I have used Groebner[UnivariatePolynomial] extensively on my procedures and I wonder whether there is an improvement in speed and memory use in Maple 2020 in relation to the version I am currently using, that is, Maple 2017.  

Many thanks.

Ed

I am doing this plot

loglogplot((.45*exp(-0.5e-1*t)+.1*exp(-.1*t))/exp(-0.5e-1*t), t = 1.4*10^4 .. 1.52*10^4);

and I got this weird abrupt change at some point: (please see the attached maple file)
 

1.mw

I guess it is due to how Maple implement those very large/small numbers.. Any thoughts?

Sort of revising fourier. I have a graph  however it gives result from -2pi to + 2pi. there must be a comand to modify plot to go from 0 to 2pi can someone give me a clue.

Rick

I have a graph with 267 nodes and 727 edges. I am trying to produce an eligible visualization of my graph but I'm getting a very crowded network. 

Code:

with(GraphTheory);
DrawGraph(Graph(M1), style = spring, symbolsize = 10, scaling = unconstrained); 

I have attatched the a JPEG file to my question to show what it looks like. I would like to space out the nodes with a more zoomed out view. How would I go about this?
 

Maple_question.mw

Hello everyone .

I asked Maple to compute a definite integral of a function, numerically. Unfortunately it does not give me any values . I briefly explain what I did.

As you can see in the picture first I define a real valued function BW_dilog(x) (with complex domain), where the function dilog  already exists in maple. Then I defined another function, V, (with real domain and codomain ). Now I need the approximate value of the bi integral of V, on a triangle. The Maple file is attached.

I would be grateful if any one could help me.

I initialized a variable name using another variable name and := . I thought that Maple would assign the value, but I soon learned by debug that the address was assigned. This led to temporary problems.

Where can I learn the rules that Maple follows for assignment by value or address ?? Do I always have to initialize with a real number, like 0, to be safe ??

Thanks.

Mike Graber

Hello (again)

I thought I won't need help with that type of question but I came across an example that says otherwise.  Here it is

vars:=[x,y,z];

model7 := [x*(-RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)-5/4)+y*alpha[1, 2]-33/(32*RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)), x*z*alpha[2, 6]+y*RootOf(64*_Z^3+80*_Z^2+1104*_Z+561), x^2*(17*RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)+17)/(alpha[1, 2]*alpha[2, 6])-17*x*y/alpha[2, 6]+2*z*x-z-(163/32+RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)^2+5*RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)*(1/4))/(alpha[1, 2]*alpha[2, 6])]

then I issued the command 

map(w->coeffs(w,vars),model7);

to get 

[-33/(32*RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)), -RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)-5/4, alpha[1, 2], RootOf(64*_Z^3+80*_Z^2+1104*_Z+561), alpha[2, 6], -(163/32+RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)^2+5*RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)*(1/4))/(alpha[1, 2]*alpha[2, 6]), -1, (17*RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)+17)/(alpha[1, 2]*alpha[2, 6]), -17/alpha[2, 6], 2]

clearly the order does not follow model7's.  

I have also tried

[seq(coeffs(expand(model7[i]), indets(model7[i], suffixed({vars[]}))),i=1..nops(model7))];

Is there a solution to it?

Many thanks (again)

Ed

I would like to analyse the graph I made and I cannot seem to find any command that gives me the average path length of an unweighted graph, is it perhaps referred as a different command? As I have tried searching Mean path length, distance and other derivatives with no useful result.

Hello

I have the following set of coefficients 

coef7 := [-1, 2, alpha[1, 2], alpha[2, 6], (17*RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)+17)/(alpha[1, 2]*alpha[2, 6]), -17/alpha[2, 6], -33/(32*RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)), -(163/32+RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)^2+5*RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)*(1/4))/(alpha[1, 2]*alpha[2, 6]), -RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)-5/4, RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)]

Considering that alpha[1,2] and alpha[2,6] are always real, how can I extract only the real solution from coef7?  

Many thanks.

Ed

Hello

I need to count and separate the nonlinear terms in a list.  Example:

w:=[[z, y, x, 1], [x*z, x*y, y, 1], [x*z, z, x*y]];

there are 4 nonlinear terms, x*z, x*y, x*z, and x*y.  

The terms can be any combination of the given variables, that is, x, y, and z.  

My solution to the problem of counting the nonlinear terms is 

aux1:=[seq([seq(nops(w[j,i]),i=1..nops(w[j]))],j=1..nops(w))];

aux2:=[seq(selectremove(x->x>1,aux1[i])[1],i=1..nops(aux1))]

res:=convert([seq(convert(nops(aux2[i]),`+`),i=1..nops(aux2))],`+`);

It works but I wonder whether there is a better solution that includes showing the nonlinear terms themselves.

Many thanks

Ed

My colleague and I are revising a paper which contains some 3dplots generated I think originally in Maple 2015 on macos as eps converted to pdf.  Originally they were around the 100 KB size.  When I generate them again in Maple 2017 they are more like 10 MB.  He is still running Maple 2015 and get the same 100 KB size.  Any idea what is going on here ?  

Thanks Michael

EDIT:  An example is 

with(plots);
plotsetup(postscript, plotoutput = `test.eps`, plotoptions = `color,portrait,height=350,width=350`);
plot3d(x^2+y^2+1, x = -1 .. 1, y = -1 .. 1, axes = boxed, grid = [200, 200]);

I get 7.6 MB my colleague with Maple 2015 gets 56 KB.  I tried it wtih Maple 2017 on a server I have access to also 7.6 MB.

my_euler := proc (func_y, x_value, y_value, n, h) 
local point_list, d_x, true_f, true_f_v; point_list := [10^(-n), 0, n]; 
true_f := unapply(func_y, x, y); 
d_x := abs(point_list[2]-point_list[3]); 
while d_x < point_list[1] do 
    true_f_v := true_f(x_value, y_value); 
    y_value := y_value+h*true_f_v; 
    x_value := x_value+h 
end do; 
return y_value 
end proc

I am using Maple to implement Euler's method, it requires 5 parameters:

• func_y (The general form of ODE)
• x_value
• y_value
• n (The accurate digits, I do not know how to control the accurate digits)
• h (The step size)

So, I do not how to control accurate digits (4 accurate digits), can you teach me how to finish this part?

Hello.

I'd like to extract numerical data from the plot of a implicit function and write it to the txt file. But, unfortunately due to a strong oscillating function and as a consequence extremely dense meshgrid I got a message that [Length of output exceeds limit of 1000000]. How to resolve this problem? Below is my code

restart;
R0 := 1+w_c*(sum((2*(-1)^(n+1)*Pi^2/n*n)*t*sin(2*Pi*n*mu/w_c)*cos(Pi*n)*exp(-2*Pi*n*G/w_c)/(w_c*sinh(2*Pi^2*n*t/w_c)), n = 1 .. 3000))/Pi-mu;
with(plots, implicitplot);
G := 0.; t := 0.1e-2;
R1 := implicitplot(R0, w_c = 0 .. 5, mu = 0 .. 3, gridrefine = 10):
data := getdata(R1);

Thank you in advance.

Consider two polynomials p and q in t. For example,  and . I want to find . But before I find it, solve an inequality and obtain that . After that when I evaluate , I dont want maple to return  as Gcd because  and thus the factor  is an unwanted common divisor. Is there a way to tell maple that "find the Gcd over a spesific domain". Because, otherwise maple needlessly spend time for finding the gcd. Any help would be appreciated.

I have a bivariate polynomial in x,y,say P, and a parameter, say d, appears in P. I want to find d for which P has at least one non trivial factor. Is there  a fats way to do this in maple. Any help would be appreciated.