I want to find fundamental matrix of the system: X(t).

Actually I need A=X(T) where T is 2*Pi.

So then I can find whether the solution is stable.

The problem is, I don't understand how to find X(t) in Maple. 

Tried to solve numerically with dsolve at t=T but the next step is not obvious.

Eq=z"(t)+3z'(t)+2z(t)=24*(exp(-3t)-exp(-4t)) how to find the gereral solution of this equation. Thank you.

The last months Maple 2020 suffers from frozen interface behavior:

I simply wanted to save a file, but that resulted in a frozen window:

After 10 minutes the file explorer window appeared, but also this screen is unresponsive.

I reinstalled Maple last month, but that didn't help. Remarkably, the problem comes and goes. It seems to me that some java problem is making my life difficult.
Any ideas?
kind regards,

Harry

ps I ran the process monitor of Sysinternals, but I have no idea if this has any relevance to the problems:

11460 RegOpenKey HKCR\Local Settings\Software\Microsoft\Windows\CurrentVersion\AppModel\PackageRepository\Extensions\windows.protocol\Maple.cwmaple.2020 NAME NOT FOUND Desired Access: Read

11460 ReqQueryValue HKCR\Maple.cwmaple.2020\URL Protocol NAME NOT FOUND Length: 12

11460 RegOpenKey HKCU\Software\Classes\Maple.cwmaple.2020  NAME NOT FOUND Desired Access: Maximum Allowed

Would like to export a list into a text file

when I tried , it show ... 1234 items... , can not export a whole list into text file.

[[[0,0,0,0]], [[0,0,0,0]], .....]
thousands of [[...]] elements

Hi, I would like to parallelize the double for loop. I am computing pairwise SPolynomials like so

for i from 1 to n-1 do

for j from i+1 to ndo

spol:=Spol(poly[i],poly[j], tdeg(op(vars))):

...

od:

od: 

I would like to parallelize this code, here is what I have done:

at_node:=proc(p1,p2,vars, polynomials)

spol:=SPolynomial(p1,p2,tdeg(op(vars))):

if NormalForm(spol, polynomials, tdeg(op(vars)))=0

return [1,0]:

fi:

end proc:

Grid[Setup]("local", num_nodes=4):

Grid[Set](at_node): # below is the main loop that fails

for idx from 1 to n-1 do

out:=Grid[Seq](at_node(polynomials[idx], polynomials[j], vars, polynomials) j=idx+1, n):

od:

The loop above fails due to the error when calling normal form. It seems that the at_node function accepts an incorrect input for p1, a list of polynomials instead of a single polynomial. Is there a way to parallelize double for-loop with Grid like that? I am not sure where my error is.

Hello everyone,

I think that I accidentely deleted a file from inside of a Maple workbook. Is there a way to restore it inside of that workbook?

Regards,

Is it possible to generate a XMLElement by using part of the code to be generated with a string, or are the only methods a strict use of AddAttribute and AddChild?

Hope the code below explains what I mean. The first line is a strict copy of a declaration in the help file.

The question is if I could use some part of the definition which is saved in the str variable and combine it into the first declaration?

Download xml_string.mw

I am trying to plot generator reactive output (Q) over a range of generator power output (P) with field current (Ifldc) and terminal voltage (Et) constant using “solve”. The system of equations includes an interpolating fiction Ifld(el).

I’m looking for some help as to how to configure a solution. Attached are a few of my failed attempts.

The upload of my file deleats the "solve" fo my first try it is:

Download Qcalc1.mw

why setting interface(warnlevel=0); makes dsolve change the form of the final solution to an ODE?

Is this to be expected? Help on warnlevel 0 says to just suppress all warnings. 

In this example, both solutions are equivalent. One is just simpler than the other.

But now I am worried if this setting could affect dsolve in other ways not yet anticipated.
 

Download warnlevel_difference.mw

btw, the same thing happens with warnlevel 2. i.e. answers look different.

But with warnlevel 3 and 4, now dsolve gives the same answer. 

SInce it seems default is warnlevel 3, it seems internally, dsolve takes different path depending on warnlevel setting? 

Edit

Here is a movie. I am using windows 10.

Edit: Here is another video. Tried now with fresh start of Maple. i.e. closed Maple and started it again.  Using worksheet. No other worksheet was open. This is what I found. Initially it gives the longer solution. After couple of tries, it then changed to the simpler one

Please I have an issue with the attached plot code. Can you kindly help to correct it? 

restart:
interface(rtablesize=infinity):
B:=<<0,0.05,0.1,0.15,0.2,0.25,0.3,0.35,0.4,0.45,0.49,"0","0.05","0.1","0.15","0.2","0.25","0.3","0.35","0.4","0.45","0.49">|
	<14.73,14.4,14,13.4,12.67,11.67,10.4,8.67,6,3,0,"14.73","14.4","14","13.4","12.67","11.67","10.4","8.67","6","3","0">|
     <-0.007072,0.013309,0.033707,0.054125,0.074571,0.095056,0.115597,0.136218,0.156956,0.177867,0.199036,0.22059,0.242719,0.265702,0.289932,0.31592,0.344214,0.375124,0.408175,0.441761,0.473484,0.501857>|
	<1.34E+01,1.33E+01,1.33E+01,1.32E+01,1.31E+01,1.31E+01,1.30E+01,1.29E+01,1.28E+01,1.26E+01,1.25E+01,1.22E+01,1.19E+01,1.14E+01,1.08E+01,9.86E+00,8.58E+00,6.90E+00,4.90E+00,2.81E+00,1.00E+00,-2.86E-01>>:

B:
 
 plot([B[..,[1, 2]],B[1..1,[1, 2]], B[.., [3, 4]],B[1..1,[3, 4]], B[..,[5, 6]],B[1..1,[5, 6]],B[.., [7, 8]],B[1..1,[7, 8]],
 	  B[..,[9, 10]],B[1..1,[9, 10]], B[.., [11, 12]],B[1..1,[11, 12]],B[..,[13, 14]],B[1..1,[13, 14]],B[.., [15, 16]],B[1..1,[15, 16]],
 	  B[..,[17, 18]],B[1..1,[17, 18]], B[.., [19, 20]],B[1..1,[19, 20]],B[..,[21, 22]],B[1..1,[21, 22]]],
 	  legend = ["","Experimental","","Simulation"],
 	  style = ["line","line","line","line","line","line","line","line","line","line","line","line","line","line","line","line",
 	 		"line","line","line","line","line","line"],
 	  color=[blue,red], labels=[`V (V)`, `Jsc (mA/cm^2)`]);
 

Download Graph_Example.mw

I found a condition for p, q that N=pq can be factored in plynominal time using Maple 2020.
Is fllowing Hypothesis and Proof is right?

Hypothesis

       N=pq  p and q are large prime respectively.
         R=q/p  q > p  R is very close to an small integer or a simple rational number.
       
        N=pq can be factorized in time polynomial

Proof
        point[p, q] is on y=N/x
        y=N/x  and y=Rx cross at point[p, q]
        N is n digit
        upper  2 digits N2  round off the 3rd digit
        upper  3 digits N3  round off the 4th digit
        upper  4 digits N4  round off the 5th digit
        
        y=N2/x and y=Rx cross at point[p2,q2]
        y=N3/x and y=Rx cross at point[p3,q3]
        y=N4/x and y=Rx cross at point[p4, p4]

        But we only know N.

        Let line up candidates point[p2,q2] , point[p3,q3] and point[p4, p4]

       N2 < 99  i=1..10 j=1..10
       R2=i/j
       f2=N2/R2 - j^2
       dn2=abs(N2-R2*j^2)   

      N4 < 9999  i=1..99 j=1.. sqrt(N4)
      R4=i/j
      f4=N4/R4 - j^2
      dn4=abs(N4-R4*j^2)

     Point[j, i] that have  small f2 and dn2 can be nominated as candidate for point[p2, q2]
     Point[j, i] that have  small f3 and dn3 can be nominated as candidate for point[p3, q3]
     Point[j, i] that have  small f4 and dn4 can be nominated as candidate for point[p4, q4]

    Find cross point[px, qx] of y=R2x and y=N/x , y=R3x, y=N/x and y=R4x, y=N/x
    Find the nearest prime pn for px and the nearest prime qn for qx
   
   pn*qn=N  bingo!

   Number of candidates are finit.
   You can factorized N=pq in time polynomial.
                                   
                                                                       Q.E.D. ?

In addition, using "https://www.mapleprimes.com/questions/228532-Strange-Factorization"

Rang from p - half digits of p to p + half degits of p and /or range q - half digits of q to q + half degits of q  N=pq can be factored in plynominal time.

Hi, everyone!

I'm trying to do some computations with (truncated) multivariable power series, which I'd like to put into Hironaka standard basis form.  This is almost the same as a Groebner basis, except that the "leading" terms have smallest degree instead of largest.  This requires slight changes to the algorithms in order to make sure they terminate.  Does anyone know if this has been implemented in Maple or have a good way to fake it?  Here's what I've thought of:

• Using the Groebner package with grlex_min instead of grlex.  The documentation warns that this may not terminate, and sure enough, it doesn't.  (At least not before my computer runs out of memory.)
• Replacing the truncated power series with their palindromes, using the Groebner package, and then switching back, making sure all the degrees are correctly accounted for.  This should work, but it's going to be a major pain.
• Reimplementing the Groebner routines.  I'd really rather not, but I'd love to know if anyone else has.

Anybody have any other ideas or suggestions?

Thanks!

----Josh

Hi,

I tried to find the set of real parameters a1, a2, a3, a4 and u1, u2, u3 which make a subalgebra L an ideal of a finite real Lie algebra LieAlg. Unfortunately, the "Query" command with the "Ideal" argument returns an error message that I can't get around. What should I change in this command?

restart: 
with(DifferentialGeometry):
with(LieAlgebras):
#
DGsetup([x1,x2,x3],R3):
#
Lie_Generators := [D_x1*x1+D_x2*x2+D_x3*x3, D_x3*k^2*x1+D_x1*x3, -D_x1*x2+D_x2*x1, D_x3*k^2*x2+D_x2*x3, D_x1, D_x2, D_x3]:
#
LieAlg:=LieAlgebraData(Lie_Generators):
#
DGsetup(LieAlg):
#
L:= evalDG([e3+u2*e5-u1*e6,e2-u3*e5-k^2*u1*e7,e4-u3*e6-k^2*u2*e7,e1-u1*e5-u2*e6-u3*e7]);
Sub_Alg_L:=LieAlgebraData(L);
#
TrueFalse,Equations,Solutions,IdealList:=Query(L,{u1,u2,u3},"Ideal");
#
TrueFalse,Equations,Solutions,IdealList:=Query([DGzip([a1,a2,a3,a4], L, "plus")],{a1,a2,a3,a4,u1,u2,u3},"Ideal");

Thanks for your help.

Jaqr

converts a Maple polynomial into a list of its coefficients.