Unanswered Questions

This page lists MaplePrimes questions that have not yet received an answer

Maple offers the dimension “lenght” whereas MapleSim offers two types.

What is the difference between the two types length and distance?

Can they always be used interchangeably?

Hello community. I'm trying to use Maple for some study.
My goal is to get the Wiener-Hopf equation in matrix form like in the book (eq 3.56).
So at first i need the gradient of eq 3.53, the result is eq 3.55 (nabla is not printed) .
Could you please provide an example of this operation, if it is possible, thanks.


During my reaserch on diffusion I am arrived at the integral with argument

exp(-1/sqrt(x^2 + 1)) which Maple is not able to solve.

If some experts in solving integrals is able to solve it please keep me informed.

The file in Maple 2022 is below

primes_integral_diffusion.mw

Hello everyone!

I use this procedure to open my inbox:

>restart;
ShellExecute := define_external('ShellExecuteA', hwnd::(integer[4]), lpOperation::string, lpFile::string, lpParameters::string, lpDirectory::string, nShowCmd::integer[4], 'RETURN'::integer[4], LIB = "C:\\WINDOWS\\SYSTEM32\\shell32.dll"):
OpenBrowser := proc(someURL::string := "http://")

ShellExecute(0, " ", someURL, " ", " ", 1); NULL;

end proc:

Case 1:  I entered the correct email address of my friend who sent me the mail

>OpenBrowser("https://mail.google.com/mail/u/0/?tab=rm&ogbl#inbox/xxxxxxGqRZXPKXGzrrSrfHscdNWspRJF");

As a result, the content of the message I received was opened with full information.

Case 2:  When I enter an arbitrary email address that is not my friend, the result is that no content is displayed.

>OpenBrowser("https://mail.google.com/mail/u/0/?tab=rm&ogbl#inbox/yyyyyyGqRZXPKXGzrrSrfHscdNWspRJf");

On the email there is only the message: The conversation you requested could not be loaded.

May I ask:  Is there any Maple command to return true in case 1 and to return false in case 2 ?

Thank you very much for your help !

When I try to change the number format (decimal places) of a sequence in Maple Flow using the right hand slide out context panel all numbers in the sequence are replaced by only the first number in the sequence.  I'm not sure if it has been fixed in 2022.1

Before the adjustment ...  

Selecting fixed prompts the result to stop after the first number in the series.

 

Can anyone else confirm this issue?

As you can see in the figure below, 

it shows a very strange "font",

you can obviously see very weird spacing even inside one word...

Who knows what's wrong???

Thanks a lot.

B/R

Jankel

Good day,

I am looking for some guidance with the Syrup toolbox

I have a netlist that was generated with the Altium designer Spice simulator (XSpice based), I was able to import it into LTSpice and verrify the results.

I want to move it into maple to make use of the modellica code generation.

I then began modifying the netlist in order to meet the netlist syntax of Syrup. One of the most prominant change I needed to make was the arbitrary input nodes for my Voltage dependant Voltage sources. 

Therefore, for any line that implies arbitrary sources such as:

E_U8_E1 U8_N208620 LO
+ VALUE { IF(V(U8_N208706, 0) > 0.5, 5, -5) }

was changed to:

V1    16   17 1vdc

E_U8_E1 U8_N208620 LO 16 17
+ VALUE { IF(V(U8_N208706, 0) > 0.5, 5, -5) }

This, of course, is a non ideal workaround which brings me to question 1,

Is there a way to define a arbitrary source with the Spice parser in Syrup?

Once these changes were made, it seems the Solve function in Syrup can parse the netlist without issue, however when it gets to the Solve portion it throws the following error:

Solve("file://C:/Users/msavoy/Documents/Spice_cct/inverter_newfet_nonot.cir", 'tran');
Solve: Analyzing SPICE deck "The Apple" (ignoring this line)
Error, (in Syrup:-Solve) invalid input: rcopy uses a 1st argument, A (of type anything), which is missing

Attached is a copy of the netlist, inverter_newfet_nonot.txtI am honestly at a lost as to what could be throwing the rcopy error

Furthermore, I wanted to test out the Modellica code generation in Syurp, it appears that it does not like having subcircuits, as running the test:

V 1 0 1
L1 1 2 L
C1 2 0 C
L2 2 3 L
C2 3 0 C
L3 3 4 L
C3 4 0 C
Vshort 4 5 0
Rt 5 0 1
.SUBCKT TEST A B C Y
V1 14 15 1
EINT YINT 0 14 15
+ VALUE {IF(V(A) > 0.5 && V(B) > 0.5 && V(C) > 0.5, 1, 0)}
RINT YINT Y 1
CINT Y 0 1n
.ENDS TEST
.end

provides the error of:

test_c := ToModelica("file://C:/Users/msavoy/Documents/Spice_cct/test_cct_RCL.txt", 'probes' = ["Rt.v"], 'parameters' = {C = 2, L = 1});
Error, (in Syrup:-ToModelica) invalid input: nodeToModelica expects its 1st argument, node, to be of type nonnegint, but received Y

Is it possible to define a sub circuit in a netlist that is to be converted to Modellica, or do all subcircuits need to be defined in their own file?

Thank you

in the context of solving an ode, sometimes the constant of integration that will satisfy an initial condition is +infinity or -infinity.

But Maple's solve does not find such solutions to the constant of integration. It only can solve for finite value if it can.

When this happens, I manually try taking the limit as the constant of integration goes to +- infinity, until I get an equation where both sides are the same or fail, and then give up.

I was wondering if there is a way or different command/package which will find solution such as infinity (which is valid solution to constant of integration).

Here are two examples

ode:=diff(y(x),x)=1/(LambertW(-exp(-1+_C1+x))+1);
ic:=[diff(y(x),x)=1,x=0];
eq2:=eval(ode,ic);
solution_for_constant := solve(eq2,_C1,'allsolutions'=true,'tryhard'=true);

Maple can not solve for _C1. It gives

But when trying manually few values, I find that _C1=-infinity satisfies the equation

limit(rhs(eq2),_C1=0);
limit(rhs(eq2),_C1=1);
limit(rhs(eq2),_C1=-1);
limit(rhs(eq2),_C1=infinity);
limit(rhs(eq2),_C1=-infinity);

The above shows that _C1 = -infinity is the constant of integration. Another simpler example

eq:=exp(-1 + _C1) = 0;
solution_for_constant:=solve(eq,_C1) assuming real;
limit(lhs(eq),_C1=-infinity)

The above shows that _C1=-infinity is solution for exp(-1+C_1)=0.  which one can see by just looking at it as exp(-infinity)=0.  Adding assumptions did not help.I also tried symbolic option.

I am not familar with SolveTools package, may there is something there.

So for now, my code just try the limit until it finds solution or gives up.

Any suggestions if Maple itself can find such solutions?

Maple 2022.2

if isolate fail, then it returns back the input equation. But if solve failed to solve for the variable in question, it returns either NULL or empty list, or empty set (depending on the input). So it is easy to check if it failed or not.

How does one check that isolate failed? Should I check the left side of what isolate returns is the variable I am solving for? For an example,

sol:=isolate(-2*y-cos(y)+x+sin(x)-_C1 = 0,y)

returns back -2*y-cos(y)+x+sin(x)-_C1 = 0

Is the following the correct way to check if isolate solved the equation or not:

sol:=isolate(-2*y-cos(y)+x+sin(x)-_C1 = 0,y);
if lhs(sol)=y then
   print("it solved it. Soltion is ",sol);
else
   print("Failed to solve it. Try solve command now ");
fi;

Just wanted to make sure as help for isolate does not mention anything about what happens if isolate can't solve the equation.

Maple 2022.1

My old company went belly up during the COVID period. My old email address is now dead as a doornail.

I can login to MaplePrimes using the old email address, post questions, etc.

However, I can't change my account email address becaue Maplesoft sends a verification message to the OLD email address.

If I post a question, I can read the replies here. However, any replies sent to my OLD email address just disappear.

How do I change my account email address under this situation?

Thanks.

Hello everyone,

I am trying to solve a system of 4 ODEs that describe a physical system, however, I get the message:

Error, (in dsolve/numeric/bvp) matrix is singular

Any help is much appreciated. The initial conditions are such that to find solution in steady state, that means, v(0)=v(period) and so on with all variables.

Download LLCcircuit_SteadyState_numerical.mw

Good day. 

I have been looking into the time series features in Maple and was eager to apply the models to one specific example containing 47 data points (attached).

When I run the ESM routine, Maple provides a forecast based on a (A,N,N) configuration. You will notice that the forecast for the following 12 data points is a constant value. I have also noticed this for several other data set examples and I would have expected the predictions to vary across the next 12 data points.

Does the (A,N,N) configuration in Maple automatically provide an optimal forecast and can anyone advise me on how to specify all possible combinations of (error, trend, season) models?

Thanks you for reading.

MaplePrimes_TS_Example.mw

solve((∂(-    ∇(f) ))/(∂ t)+((DotProduct(v[0],∇f))*(1-e(DotProduct(B,Omega)))+(c[s0]^(2)*rho[1])/(rho[0])(1-e(DotProduct(B,Omega)))+e(CrossProduct(∇ f,B))*Omega-e((DotProduct(-∇f,Omega))*(DotProduct(B,∇)))*(-∇f)+e(E)*(1-(DotProduct(B,Omega)))+e^(2)(DotProduct(E,B))*Omega-e*((CrossProduct(E,Omega))*(∇(-∇f)),rho[1]);

Hi,

Since a couple of years ago,  SQLite has been enriched with a bunch of new math functions not existing in previous versions: acos, asin, atan, atn2, atan2, acosh, asinh, atanh, difference, degrees, radians, cos, sin, tan, cot, cosh, sinh, tanh, coth, exp, log, log10, power, sign, sqrt, square, ceil, floor, pi. 

Examples: In SQLite version 3.39.4 2022-09-29 15:55:41 we can invoke:

sqlite> select pi();
3.14159265358979

sqlite> select power(2, 3);
8.0

sqlite> select floor(2.35);
2.0

Package Database[SQLite] in Maple 2022.2 does not recognize these functions.

In oldest versions of Sqlite3 we were able to add these functions after loading an external extension with sqlite3 api function load_extension() (see  https://sqlite.org/contrib/download/extension-functions.c), but his option is blocked in Maple:

dbName := "d:/sq3_maple/etc.db":
sq3Extension := "d:/sq3_maple/extensions.sq3":

with(Database[SQLite]);
[Attach, Bind, ClearBindings, Close, ColumnCount, ColumnNames, 
  Execute, Fetch, FetchAll, FetchRow, Finalize, Open, Opened, 
  Prepare, RESULT_BUSY, RESULT_DONE, RESULT_ROW, Reset, Step]

conn := Open(dbName):
Execute(conn, sprintf("SELECT load_extension('%s')", sq3Extension));
Error, (in Database:-SQLite:-Execute) not authorized

Am I missing something? Any way to add these functions to SQLite in current version of Maple?

Thanks in advance.

César Lozada

PS: SQLite is updated in Mathematica 13.1

 

 

 

Dear all

I construct by hand the two matrices L and U so that A= LU ( LU-factorization) 
I would like to find the number of arithmetic operations required to obtain the matrices 𝐿 and 𝑈

Number_arithmetic_operation.mw

Thank you

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