`assuming`([dsolve({a3(0) = 0, diff(a3(z), z) = -K*a10*a20*sqrt(1-a3(z)^2/a10^2)*sqrt(1-a3(z)^2/a20^2)})], [positive])

which returns

a3(z) = -JacobiSN(z*a10*K, a20/a10)*a20

While in Mathematica, it yields a different solution:

a3(z) = -JacobiSN(z*a10*K, a20^2/a10^2)*a20

Which is right?

Thanks in advance.

Hi,

Consider the following planar dynamical system(PDS) with parameters r, p1, s, n:
a:=(r+1)*(1+p1*s)/(2*(1-P1))-1/(n^2);
b:=(r+1)*(3-r)*(1-p1*s^2)/(8*(1-p1))-3/(2*n^4);
c:=(r+1)*(3-r)*(5-3*r)*(1+p1*s^3)/(48*(1-p1))-5/(2*n^6);
 

Hi,

I am using Direct Search Optimisation package to minimize a function however I am trying to define an equality constraint for it, but I am facing a problem when I run it. Please see the code below.

    result := DirectSearch:-Search(CHWP,[sum(d[i], i = 1 .. 7)  = 220], variables = [d = Vector(7)], assume =nonnegint,
            strategy = globalsearch, method = cdos, evaluationlimit = 10000, objectivetarget = 10^(-10));

CHWP is the name of my procedure which works with any other type of constraint. d is my variable which I have defined as a vector. when I run this it starts with different combination of numbers for d[i]s however the error comes in when it all of a sudden assigns some numbers to d[i]s which their sum exceeds the limit which I have defined (220) in this case and when this happens the procedure will give an error which is normal for the function which I have defined since a number bigger than 220 does not make sense in this case. I would be glad if you can help me with this. Many thanks.

I'm using Maple to solve academic problems.
At a certain stage, I need a loop to perform numerical calculations, from where I extract a graph. However, each step takes a long time and therefore, I would like to evaluate the performance of the result at each step of time.
To simulate my calculation, I created a test code:

restart:                                                                  # Restart
with(Threads):                                                      # To use Sleep()
a := 2*((ceil(rand()/10^10)-50)*(1/10)):                # Random Value
b := 2*(ceil(rand()/10^10)-50):                             # Random Value
c := 2*ceil(rand()/10^10)-100:                             # Random Value
f := proc (x) options operator, arrow; a*x^2+b*x+c end proc;                  # Generic function that i'm ploting.
np := 10:                                                              # Number of Points i'm ploting
vmax := 10:                                                         # Maximum funcxtion value
VAR1 := Matrix(np+1, 2, proc (m, n) options operator, arrow; if n = 1 then (m-1)*vmax/np else 0 end if end proc):       # Declaring VAR1 as a "null" matrix

for i to np+1 do                                                  # Loop Start
VAR1[i, 2] := f((i-1)*vmax/np):                           # VAR1 value update
print(plot([VAR1], x = 0 .. vmax,  gridlines)):                           # Ploting VAR1
Sleep(.25):                                                         # Simulating longer processing time
od;

However, all graphs are displayed simultaneously after the last step of the for loop.
I would like to print the result (output) after each time step, plotting a new graph for each time an iteration ends.
Would anyone know how to do this?

Thank you for your help.

Hi,

fsolve( [Eq1, Eq2, Eq3, Eq4], {x, y}) is not possible since the number of variables are less than number of equations. Are there other ways to solve simultaneous equations?

Thanks,

Baharm31

Hi,

I am looking for an animation on conics according to the eccentricity? ideas?

Thanks

 How to use the command  "latex" to write a table with, say,

3 polynomials on the same line, separated by an "&" ?

The idea is to get  a program to produce tables of polynomials in LATEX format.

Hi all;

I hope all is well with you.

I am regular user of Maple for 7 years. I just reinstalled it to a new version, Maple 2019.

After installation, which was very smooth and without any unexpected problem, I opened a new document and entered a simple task; “sqrt(4);” the answer was

1.81847767202745*10^(-58) + (7.53238114626421*10^(-59))*I

I am pretty sure that I am missing something. The answer is obviously incorrect and there is a problem, but where.

I would be thankful if someone could help me with this issue.

Best

Farzad

A tank contains 1200 gal of water in which 150 lb of salt is dissolved initially. 50 gal of brine, each (gallon) containing (1+sint) lb of dissolved salt, runs into the tank per minute. The mixture, which is kept uniform by stirring, runs out of the tank at the rate of 30 gal per minute. Denoting the amount of salt in the tank at any time i as m, (a) formulate an ordinary differential equation for studying the dynamics of the amount of salt in the tank, (b) solve the differential equation manually, and (c) write a MATLAB mfile program to solve the differential equation using dsolve command and plot the dynamic response of the system for OSIS 7.5 hr with At = 0.5 min.

I'm trying to compute:

evalf[32](ln(1+exp(-64)));

and got:

1.6039999999999999999999999998714*10^(-28)

But I think it should be something close to:

evalf[32](exp(-64));

i.e:

1.6038108905486378529760870341423*10^(-28)

Is this a bug?

Hi all,

I'm using dsolve (numeric) for a system of ODE with initial conditions.

Is it possible to show (at the same time with solving) the values of time and an unknown when solving a system of ODE before the end of calculation. Of course, the calculation time is high and I want to know before the calculation is finished if the solution is converging.

Also, I use the option range in my calculations from 0 to 200s (seconds) and more. I do'nt know how I can speed up the solution with less memory.

Please find in the attached file an example.

dsolve1_1r.mw

Thank you in advance for your help.

Dear Maple users

I have had problems with Maple 2020. I am using Windows 10, by the way, and have several versions of Maple installed: 2019, 2018 and even 2017. Now however I am unable to open a Maple file from Windows Explorer either by double-clicking or by right-clicking and choosing "Open with" Maple 2020. Nothing happens when I try so! It works properly when I choose older versions of Maple. I have about the same problems on another computer, an Ultrabook. It is really a pain having to open Maple 2020 and then having to browse all the way down a file path ... 

NB! I have tried reinstalling, but it didn't help!

I hope someone have an idea how to solve this issue. Can it be solved in the Windows Registry?

Regards,

Erik

Hi,

I need to plot a contour plots of x versus f that satisfy two following equations

2.884460657-2.884460657*sqrt(1-.6933705250*x)-5.000000000*f*(1-(1-.8*x)^.2500000000)-(12.50000000*(1-f))*(1-(1-.32*x)^.2500000000) = 0;

1/sqrt(1-.6933705250*x)+1.250000000*f/(1-.8*x)^.7500000000+(3.125000000*(1-f))/(1-.32*x)^.7500000000 = 0

How can I do that by Maple?

If the coefficient of x can be changed from 0.1 to 0.6, what is your suggestion(s) to  repeat the above process for each of these coefficients?  

I have been using Alex Potapchik & & Alec Mihailovs' procedure for generating a multivariate sample

https://www.mapleprimes.com/questions/37539-Generate-Data-From-A-Multivariate-Normal

How can I plot the eigenvectors in the 3D scatterplot?

Download Plot_eigenvectors_in_3d_scatterplot.mw

Coming across this post upon investigating relational symbols available in Maple that I am yet to use, (the first listing in the search results):

https://math.stackexchange.com/questions/1929439/what-does-square-subset-and-square-union-symbol-mean

I again wish to reinforce the motive behind a post I previously made, and that is that a stack exchange maple community would be beneficial to education in general.

I also want to point out that I have no stake in this, I am an average user of both the Stack exchange mathematics domain, and an average user of Maple, neither of which I am employed by or would be in any realistic forseeable future.