with(plots, implicitplot);

eqn := (1 + ln(x))/x = 0;

plot1 := implicitplot(eqn, x = -10 .. 10, y = -10 .. 10)

I'm trying to plot this equation, however no lines are showing up on the graph at all. Am I doing something wrong?

The interval I set seems to be correct, double checked it in other software

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

This is an issue I had for long time. Though to ask about it.

Any one who used Database[SQLite] in Maple probably know this.  I'd like to do kernelopts('assertlevel'=2): but this does not work when using Database[SQLite] as it raises assertion failed, due to the way data is read from database and converted to Maple variable.

It happens at the statement 

         variable_to_read := Database[SQLite]:-FetchAll(stmt); 

For an example, the table I have in sql, has many fields. some are strings and some are integers. Lets say I want to read field called run_it corresponding to rowid I enter. So I do this in Maple

local run_it::integer;
.....
counter :=1;

stmt := Database[SQLite]:-Prepare(conn, cat("SELECT run_it FROM PROBLEMS WHERE rowid=",convert(counter,string),";"));    

run_it := Database[SQLite]:-FetchAll(stmt); 

The assetion error happens at the second call above. 

Error, (in dsolver_test:-MAIN_STEP) assertion failed in assignment, expected integer, got Matrix(1, 1, {(1, 1) = 1}, order = C_order, attributes = [source_rtable = (Array(1..1, {(1) = 1}, order = C_order))]) 
 

Once I remove kernelopts('assertlevel'=2): everything works fine with no problems at all. So I been running my program for more than a year now without the assert set.

Since I have hundreds of  such calls, and I do not think try/catch will work here, any one knows of a way to handle this, so I can turn on assertlevel to help catch any other problems some where else in the program, and still use SQLite ?

I could make an example if needed. I would need to create new database file and so on. This will take time.

Maple 2020.2

ps. Database[SQLite] works very well and very fast. I am surprised how fast it reads the data. few thousands records, each is 25 fields, and it does it in few seconds. Good implementation.

Edit

I found that by removing all the type specification on my Maple variables, that I read the SQL data into using FetchAll(stmt);  it now works!

So I am able to now use kernelopts('assertlevel'=2):

So intead of doing  

local local run_it::integer;  and then call SQL, I just now do  local run_it; with no type.  I had to remove the type on many such variables I had.  Now no assertion error any more during the SQL calls.

This works for me for now. I should have done this long time ago, I just did not think about it before. I would have liked to keep the type here.

Edit: I see answer below that allows me to do this by changing assert level just for the call to SQL which is good solution.

In Maple 2020.2, and after I changed to interface(warnlevel=4); then once in a while, I now see this message 

                                  Warning, persistent store makes readlib obsolete

followed by name of the file and the line number. It always happen at calls to timelimit(the_time_limit,:-dsolve(....

It seems harmless so far, as I have not seen any side effect.

I googled and the above, and see few places where it shows up, but no clear explanation what it is and what it means. But the messages I saw at google are a little different. They look like this

               WARNING: persistent store makes one-argument readlib obsolete

While the one I get is a little different as you can see. (no one-argument in it)

I am using my own package in .mla file during running the code if this makes any difference.

Is there any place where it explains what this means and why it happens sometimes? Sorry, can't make MWE, since it seems to happen at random. But I noticed it always happens at call to dsolve when I saw it.

Maple 2020.2

Physics 884

Windows 10
 

Note: If I remove the cosh from P1 then everything works fine.

Download DP_sheet_0.1.mw

I'm trying to make a table of values as a data table.  The problem is that it's making more rows than loops, I'm not able to make an empty DataFrame, and that I have to add an extra row to align the values, so I need to remove a row, and change the indexes.  Any help with making data tables work properly, would be greatly appreciated.

```

newt := x -> evalf(x - f(x)/D(f)(x));

f:= x -> x^6-2; # function to analyze

rt[0] := 1.5; #x0 value

n_error[0]:=1.5-newt(1.5): #error of first estimate
     

DF := DataFrame( <x|n_error>):# create a dataframe to store estimates, and error rates
for count from 0 to 10 do; nerror[count]:=abs(x[count]-x[count-1]);    rt[count]:=x[count-1];
x[count + 1] := newt(x[count]); DF:=Append(DF,DataSeries(<rt[count]|nerror[count]>),mode=row);    
end do:

NewtonData:=DataFrame(Remove( DF, 2, mode=row)):
NewtonData

```

In the below paper 

ODEs are solved by using Matlab Software

Is it possible to solve this in Matlab software?  [I think you mean Maple!--Carl Love]

I have attached the Article

j.physa.2019.123959.pdf

I am trying to run a Groebner Basis computation below in a for loop a few times to get an average running time.

start := time[real]():
gb := Groebner[Basis](polynomials, tdeg(op(vars)), characteristic=2^29-3):
finish := time[real]() - start:

Because Maple apparently caches the result, i was wondering if there is a way to undo this caching? Or better yet, is there a built-in tool taht would do this time measurement multiple times?

I have the following link with data that I want to import to Maple and plot... any ideas how I can do that? Thanks.

https://www.gw-openscience.org/GW150914data/P150914/fig1-observed-H.txt

restart;
N := 10;
h := 0.1e-1;
print(??); # input placeholder
r := 0.2e-1;
for n to 10 do xn := sin(h*n) end do;
print(`output redirected...`); # input placeholder
                         0.009999833334
                         0.01999866669
                         0.02999550020
                         0.03998933419
                         0.04997916927
                         0.05996400648
                         0.06994284734
                         0.07991469397
                         0.08987854920
                         0.09983341665

for m to 10 do ym := cos(r*m) end do;
print(`output redirected...`); # input placeholder
                          0.9998000067
                          0.9992001067
                          0.9982005399
                          0.9968017063
                          0.9950041653
                          0.9928086359
                          0.9902159962
                          0.9872272834
                          0.9838436928
                          0.9800665778
eq := sum(sin(xn)*ym^5*u(x) = y, x = 1 .. 10);
print(`output redirected...`); # input placeholder
0.09012228112 u(1) + 0.09012228112 u(2) + 0.09012228112 u(3)

   + 0.09012228112 u(4) + 0.09012228112 u(5) + 0.09012228112 u(6)

   + 0.09012228112 u(7) + 0.09012228112 u(8) + 0.09012228112 u(9)

   + 0.09012228112 u(10) = 10. y
 

I do not know what the mistake is, help to solve please

I have a piece of code that solves a differential equation numerically and plots the solution, but I also want to store my values for the solution so that I can later call them easily. I want to be able to save my values for xphi for all t from 0 to 11 - not necessarily with the same variable name, it could be some k(t) - so that later when I type eg k(10) Maple gives me the value of xphi at t=10. I assume the code only requires a slight modification, but still I haven't been able to find a way to do this. Here is the corresponding piece of code. Thank you in advance.

restart;
with(plots);
with(plottools);
k := disk([0, 0], 3, color = white)

k1 := polygon([[0, 0], [3, 4], [3, 1]])
display({k, k1});
Error, (in plots:-display) expecting plot structures but received: {k1}
 

Dear people in mapleprims,

I haven't used maple for a long time.
By the way, I tried to modify a denominator part in an fractional expression, but I couldn't.

Original expression is 

a:=-(I__22-X__2)/(I__11*I__22-I__11*X__2-I__12*I__21-I__22*X__1+X__1*X__2);

#And, I want to change this to the form

b:=(X__2-I__22)/((x__1-I__11)*(X__2-I__22)-I__12*I__21);

How can I do this?

Thank you in advance.

taro yamada

Hi,

how to display the primitive in the form f^n/n . ith the command int, the response is always developed. ( i try different commands "factor",...without results) 

Thanks

QuestionInt.mw

This seems like a serious limitation of Maple module, unless I am missing something.

I am trying to refactor one of my module, putting some code in separate .mpl file, say B.mpl,  and then do, from the main module

   $include  "B.mpl"; 

 But Maple complain now that, since B.mpl has export in it, that I can't do that. 

But the code inside B.mpl works fine if I copy it back and paste it inside the module, in the same location where the $include  "B.mpl";  is

Here is an example. (Since I can't use $include  "B.mpl";  in worksheet, Maple does not like it, I replaced it in this example by read "B.mpl";

(btw, both the syntax  module A()   and A:=module() seem to be equivalent), the problem shows up with either form)

I also tried with ";" and witout ";" at the end of the $include , it still gives same error.

restart;

currentdir("....."); #set directory to where the folder is


module A()

read "B.mpl";

 export foo:=proc()
  0;
 end proc;
end module;

Where the file B.mpl is

export boo:=proc()
return 0;
end proc; 

How is one supposed to refactor long file to separate files if can't leave export on those proc's?  

If I put everything in one .mpl file, it works

module A()

#read "B.mpl";  

export boo:=proc()  #this proc was in B.mpl
return 0;
end proc; 

 export foo:=proc()
  0;
 end proc;
end module;

I did more testing, and found that this seems to be an issue in Maple 2020.2. Because I just tried the same thing in Maple 2019 and it worked there ! i.e. no error.

Any one knows what is going on? 

Maple 2020.2, Physics 884.   Windows 10.

Here is screen shot. Same code. Works OK in Maple 2019.2 but gives error in 2020.2