Preben Alsholm

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19 years, 237 days

MaplePrimes Activity


These are replies submitted by Preben Alsholm

@Christopher2222 Thank you!  Indeed there is a help page for Matrix Browser in Maple versions 2021, 2022, and 2023.

Whereas I can get double clicking in Maple 2024 work without any problem I'm not able to do that in those other versions. That's what made me write that it is a new feature.
I don't know why the feature doesn't work for me in those previous versions. They are on the same computer as Maple 2024.

PS. I checked on old laptop, which also has Maple 2021.
Same refusal to react to double click.
PPS. It has to do with my setting of typesetting. I use standard in all versions including Maple 2024.
Double clicking works on the previous versions only for typesetting = extended.


 

@C_R I looked at the help page ? Browse Matrix: Viewing Arrays, Matrices, or Vectors.

I agree that the Display setting Structure combined with a Colormap setting of Cool (or Hot) shows a color that doesn't correspond with the legend, but only if all elements are actually zero.
Same error with Display = Magnitude

This Matrix Browser is a new feature in Maple 2024.
This appears to me to be a bug.
If you consider  Matrix(11,11,fill=17)  then there is no problem.

Why expect a black image?
Try experimenting:
 

LinearAlgebra:-RandomMatrix(11,11);
Matrix(11,11,fill=17);
Matrix(11,11,(i,j)-> `if`(i=1,j,5));
Matrix(11,11,(i,j)-> `if`(i>1,j,5));

You could also experiment with the menu Colormap inside the browser.
There you can choose Grayscale, Hue, Hot, or Cool.
If you choose Cool your Matrix(11,11) will be black; choosing Hot it will be white.

@Thomas Richard I got my old laptop up and running and could just confirm that.

I keep that computer simply because it has my old Maple versions.

@ On older versions kernelopts(versionnumber)  doesn't exist, but kernelopts(version) does.
On this computer I have besides the most recent versions Maple 12; no kernelopts(versionnumber)
.

I get the same crash in Windows 11 and Maple 2024.0.
With certain assumptions I get a result:
 

restart;
sol:=(3^(1/2)*u(x)-1/3*3^(1/2)+(3*u(x)^2-2*u(x)-1)^(1/2))^(1/3*3^(1/2)) = x^(1/3*3^(1/2))*c__1;
eq:=eval(sol,u(x) = u);
plot(lhs(eq),u=-5..5); 
solve(eq,u) assuming x>1,c__1>0; # OK
# solve(eq,u) assuming x>1,c__1>-1; #Crash

 

@Ronny Yes, MultiSeries is implemented as a package.
Technically, this means it is a module with option package.
Executing with(MultiSeries) makes its content:
[AddFunction, FunctionSupported, GetFunction, LeadingTerm, RemoveFunction, SeriesInfo, asympt, limit, multiseries, series, taylor]

available in the short form as in this case limit.

This can be very convenient.

Even after having executed with(MultiSeries), the usual limit is still available as :-limit
 

with(MultiSeries);
limit(CylinderU(0,CylinderU(0,x)),x=0); # Fine
:-limit(CylinderU(0,CylinderU(0,x)),x=0); # The old wrong result.

 

int(A,x=0..xx,method=_RETURNVERBOSE);

The only successful are ftoc and msftoc with result xx*exp(-1/2).

The same result if simplify(A) is the input. Somewhat strange!

Well, it's somewhat better if you assume that n::posint:
 

is(G(2*n) = G(2*n + 1) + G(2*n + 2)) assuming n::posint;

Certainly checking concrete cases results in true:
 

{seq(is(G(2*n) = G(2*n + 1) + G(2*n + 2)),n=1..100)}; # a set of one element: true

 

@nm In your "counter example" dsolve returns a solution, which odetest verifies:
 

ode:=exp(diff(y(x), x) - y(x)) - diff(y(x), x)^2 + 1 = 0;
sol:=dsolve(ode);
odetest(sol,ode); # 0

If I understand you correctly, by counter example you mean an example showing that this general statement is false:
"It is always better to use PDEtools:-Solve rather than solve".

Just a remark.

dsolve(ode) returns
y(x) = Int(RootOf(-x + ln(_Z) + sin(_Z)), x) + c__1.

odetest is made so that it certainly verifies solutions coming from dsolve.
PDEtools:-Solve, odetest, and dsolve have the same author as I believe you know.

@Axel Vogt Yes, indeed. That was a long time ago.
The procedure is here:
 

PolarForm:=proc(tal::{algebraic,list,set},e::name:='useexp')
description "Input a complex number or a list or set of complex numbers. Output the polar form r*'exp'(I*v)
or, if 'useExp' is given as a second argument, r*Exp(I*v)";
local EXP;
if type(tal,{list,set}) then return map(procname,tal,e) end if;
if type(tal,specfunc(anything,polar)) 
   then 
      if e='useExp' then op(1,tal)*Exp(I*op(2,tal)) else op(1,tal)*'exp'(I*op(2,tal)) end if
   else
procname(radnormal(polar(tal)),e)
end if
end proc;

`print/Exp` := proc(z) 'e'^z end proc;
## Examples:
PolarForm(1+I);
%;
PolarForm(1+I,useExp);
%;
eval(%,Exp=exp);
PolarForm([1+I,I,5,-3+1/2*I]);
%;
PolarForm([1+I,I,5,-3+1/2*I],useExp);

Actually, I also added this simple extension of value:
 

`value/Exp`:=proc() exp(args) end proc:
### Example
PolarForm(1+I,useExp);
%;
value(%);

 

In Maple 2024 solve treats this equation the same as in Maple 2018.

@nm I happen to be in the beta forum. I'll report this as a weakness and give a link to this page.

Note: SCR submitted.

@nm In my reply I incorrectly referred to the statement listed for definite integration. I have now corrected that.
About method = _RETURNVERBOSE the statements under definite and indefinite integration are identical.

method=_RETURNVERBOSE applies all of the known methods and reports the results for each.

It is puzzling why the "default" result isn't identical to the _DEFAULT result.
So, yes, I agree that that is strange.

But try this:
 

int(integrand,x,method=default);

Output: 2*arctan(tan(1/2*x)) + 2/(tan(1/2*x) + 1)

So method = default is different from method =_DEFAULT.

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