Dear Sir/Madam,

I have faced a problem while using Maple 18. The  warning is the following

Warning, The use of global variables in numerical ODE problems is deprecated, and will be removed in a future release. Use the 'parameters' argument instead (see ?dsolve,numeric,parameters)

This is the code

restart;
with(plots);
beta := 0.2e-1; delta := .5; PI := 10000; mu := 0.16e-1; tau := 0.3e-1; rho := 0.4e-1; epsilon := 0.4e-1; sigma[1] := 0.1e-2; sigma[2] := 0.2e-2; eta := 0.6e-1;
sys := {diff(e(t), t) = beta*(sigma[1]*i(t)+sigma[2]*e(t))*s(t)-(delta+mu)*e(t), diff(i(t), t) = tau*delta*e(t)-(epsilon+rho+mu)*i*t, diff(r(t), t) = (1-tau)*delta*e(t)+epsilon*i(t)-(mu+eta)*r(t), diff(s(t), t) = PI+eta*r(t)-beta*(sigma[1]*i(t)+sigma[2]*e(t))*s(t)-mu*s(t), e(0) = 148, i(0) = 74, r(0) = 14, s(0) = 4110};
p1 := dsolve(sys, numeric, method = rkf45, output = procedurelist);
Warning, The use of global variables in numerical ODE problems is deprecated, and will be removed in a future release. Use the 'parameters' argument instead (see ?dsolve,numeric,parameters)
Error, (in dsolve/numeric) i(t) and i cannot both appear in the given ODE
p2o := odeplot(p1, [t, s(t)], 0 .. 4, numpoints = 100, labels = ["Time (months)", " Infected  "], labeldirections = [horizontal, vertical], style = line, color = red, axes = boxed);
Error, (in plots/odeplot) input is not a valid dsolve/numeric solution

plots[display](p2o);

Maple Worksheet - Error

Failed to load the worksheet /maplenet/convert/nnn.mw .

Download nnn.mw

Hello all,   Hope everyone is safe

Does anyone know why a vector of floats as the variable for SignalPlot returnes the error:

Error:  (in SignalProcessing:-SignalPlot) unable to store  ' " " ' when datatype = float[8] 

Accel3  is vector variable reporting back as  "57850 element Vector[column]"

 SampleRate:=50000.0

When called by SignalPlot?   

SignalPlot(Accel3, samplerate = SampleRate)

I have successfully used SignalPlot without a problem before.

Regards,

Bill

Hello everyone. I want to know how I can extract terms with the lowest sum of the degree of x and of y in a multivariate polynomial (in x and y)?

For instance, if I've f(x) = 100x^2y^2 + 35x^2y + 45y, I want an output of 45y.

On the other hand, if I've g(x) = 13x^2y^2 + xy^2 + 2yx^2, I want an output of xy^2 + yx^2.

Maple Tutors allow for copying of MathML but I need LaTeX of it. Any help please?

If we have an equation for the generalized Bloch sphere i.e.,

\partial_{t}(u^{2} + v^{2} + w^{2}) = 0,

where u, v and w are functions of x and t and the initial conditions u=v=0, w=-1. Then how to plot this equation on maple?

This is an interesting exercise in setting up triple integrals in cylindrical and spherical coordinates to obtain a formula that is immediate without any calculation using the theorem of Pappus. The cylindrical integral is easy. The spherical one is hard, but Maple gives me the result off by a factor of minus one half for generic values of the two radii, but the correct result for concrete numbers! I cannot figure out what I am doing wrong. Any ideas?
http://www34.homepage.villanova.edu/robert.jantzen/courses/mat2500/handouts/torusvolume.mw

Hi,

I have an expression (functionx) that I want to convert it to a series of x with different powers. My only issue is that I cannot accept negative powers. For example, If I had functionx = cos(x) I want to convert it to 1 - 1/2*x^2 + 1/24*x^4, which can be done with a Taylor expansion.

Here the functionx is a bit complicated if I use Tylor expansion that means I only consider the approximation for a small range of x. Is there any other approximation I could use to convert functionx to a new function that has x to the power of positive values?

restart;
functionx:=(0.007334702136*x + 2.418028262*10^231*x^57 + 1.182475218*10^223*x^55 + 5.780663993*10^214*x^53 + 2.824838912*10^206*x^51 + 6.735888408*10^189*x^47 + 1.379783148*10^198*x^49 + 3.286285701*10^181*x^45 + 7.803772225*10^164*x^41 + 1.602116861*10^173*x^43 + 1.845464073*10^148*x^37 + 3.797245890*10^156*x^39 + 4.338988887*10^131*x^33 + 8.956080140*10^139*x^35 + 2.097852265*10^123*x^31 + 4.865844768*10^106*x^27 + 1.011819388*10^115*x^29 + 2.331704338*10^98*x^25 + 1.112530729*10^90*x^23 + 2.489476842*10^73*x^19 + 5.280116219*10^81*x^21 + 5.385068408*10^56*x^15 + 1.164024492*10^65*x^17 + 4.797076312*10^31*x^9 + 1.099976521*10^40*x^11 + 2.456776729*10^48*x^13 + 7.927675416*10^14*x^5 + 2.012154161*10^23*x^7 + 2.781719840*10^6*x^3)/(0.003667351068*x^2 + 695429.9599*x^4 + 4.737736934*10^(-11) + 4.169014245*10^229*x^58 + 1.070493332*10^213*x^54 + 2.111562890*10^221*x^56 + 5.432382523*10^204*x^52 + 1.403310085*10^188*x^48 + 2.759566295*10^196*x^50 + 7.144099350*10^179*x^46 + 1.858041006*10^163*x^42 + 3.641174684*10^171*x^44 + 9.493114726*10^154*x^40 + 4.856484403*10^146*x^38 + 1.276173202*10^130*x^34 + 2.487800039*10^138*x^36 + 6.555788327*10^121*x^32 + 3.372731292*10^113*x^30 + 1.737801703*10^105*x^28 + 8.968093608*10^96*x^26 + 4.635544704*10^88*x^24 + 1.244738421*10^72*x^20 + 2.400052827*10^80*x^22 + 9.166471012*10^38*x^12 + 1.754840521*10^47*x^14 + 3.365667755*10^55*x^16 + 6.466802735*10^63*x^18 + 1.321279236*10^14*x^6 + 2.515192701*10^22*x^8 + 4.797076312*10^30*x^10)^2:
plot(functionx, x=-0.001..0.001):

The reason that I look for an expression for functionx is:

I need to replace x with a series of sin and cos functions and then find specific coefficients that have that sin or cos. In the current form Maple cannot find the coefficients of sin and cos.

I hope it is clear. I have attached the main code.Expansion.mw

Regards,

Baharm31

I have a couple of symbolic expressions that I need to compare for an underlying variable chi.

The expressions are too long to enter so I have added them in a maple worksheet attached with the post (They are assigned as SW and SR). I used the solve command but get an error as 'Warning, solutions may have been lost'. The help page states that I need to simplify the inequality to get to a solution so I tried using just the numerators (it will be a lot clearer from the worksheet) but still got the same result.

Could anyone help me with this? 

ineq.mw

As of last week using Maple 2019, and now with Maple 2020, I have begun to have issues trying to export rendered plots using plot3d. Even trying a simple example such as:

plot3d(x^2+y^2, x=0..1, y=0..1); 

will return the correct 3D plot, but right-clicking the plot closes the program immediately. Has anyone else experienced a similar issue? 

Hello,friends!

I try to calculate the limit of the function, 

sin(x*sin(1/x))/(x*sin(1/x))  at point x=0,maple gives answer:1

However,actually it does not have a limit at x=0,because for the limit to exist at a point,there needs to exist a neighbourhood at the point so that all x in the neighbour have definition.

It means f(x) should have have definition at point x=0's negihbourhood,however small the neighbourhood is.If I choose x=1/(n*Pi), n belongs to integers,the function doesn't have definition.As n increase,there doesn't exist such a neighbourhood.So is it something maple should correct?

seems_wrong_answer.mw

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

Got a question regarding numeric indices in tables. Apparently every index in a table is considered alfanumeric, which means that 90 is not the same as 90.0. 

Or test["text", 90] is not the same as test["text", 90.0].

Here's the example.

Table.mw

Apparently I will need to do some numeric formatting before using the numbers as indices for the table, right?

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?
 

I am trying to graph x^(1/2) and (x^2/8) revolving around the y-axis using the ring method but I have not been able to do it. I only get the shell method. I have adjusted the functions to read x=y^2 and x=sqrt(8y). The bounds for this method is 0 to 2. No matter the commands I have tried I have not been able to get the washer method to show. I do not want to use the tutor program.