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why dsolve losses one solution when aske...

nm 11558 Maple 2025
ode dsolve differential-equations
October 22 2025
1 0

Solving an ode, dsolve says it used exact method and gives two solutions as result (correct result).

But when asking dsolve to solve same ode but now specifying that it uses exact method (i.e. same one it used itself before), now it gives one solution only, not two as before.

Why is that? Should not both commands give same result? i.e. two solutions?

> 

interface(version);

`Standard Worksheet Interface, Maple 2025.1, Linux, June 12 2025 Build ID 1932578`

> 

SupportTools:-Version()

`The Customer Support Updates version in the MapleCloud is 29 and is the same as the version installed in this computer, created June 23, 2025, 10:25 hours Eastern Time.`

> 

Physics:-Version()

`The "Physics Updates" version in the MapleCloud is 1881 and is the same as the version installed in this computer, created 2025, October 7, 16:4 hours Pacific Time.`

> 

restart;
> 

ode:=3*y(x)^3*x^2+y(x)^4+(3*x^3*y(x)^2+y(x)^4+4*x*y(x)^3)*diff(y(x),x) = 0;
DEtools:-odeadvisor(ode);
infolevel[dsolve]:=5:

3*y(x)^3*x^2+y(x)^4+(3*x^3*y(x)^2+y(x)^4+4*x*y(x)^3)*(diff(y(x), x)) = 0

[_exact, _rational]

> 

sol:=dsolve(ode); #gives two solutions

Classification methods on request

Methods to be used are: [exact]

----------------------------

* Tackling ODE using method: exact

--- Trying classification methods ---

trying exact

<- exact successful

y(x) = 0, x*y(x)^4+x^3*y(x)^3+(1/5)*y(x)^5+c__1 = 0

> 

maple_sol:=dsolve(ode,[exact]);  #why y=0 solution do not show here??

Classification methods on request

Methods to be used are: [exact]

----------------------------

* Tackling ODE using method: exact

--- Trying classification methods ---

trying exact

<- exact successful

x*y(x)^4+x^3*y(x)^3+(1/5)*y(x)^5+c__1 = 0

> 

sol:=dsolve(ode); #gives two solutions again

Classification methods on request

Methods to be used are: [exact]

----------------------------

* Tackling ODE using method: exact

--- Trying classification methods ---

trying exact

<- exact successful

y(x) = 0, x*y(x)^4+x^3*y(x)^3+(1/5)*y(x)^5+c__1 = 0

 

 

Download why_different_solutions_maple_2025_1_oct_22_2025.mw

internal error from odetest, with _EnvAl...

nm 11558 Maple 2025
solve ode differential-equations
October 21 2025
1 0

When solution was obtained using earlier call to solve with _EnvAllSolutions := true: set, then odetest givens internal error.

When _EnvAllSolutions := false: then no error.

Why? And is there a workaround so I can use _EnvAllSolutions := true: but have odetest still work?

> 

interface(version);

`Standard Worksheet Interface, Maple 2025.1, Linux, June 12 2025 Build ID 1932578`

> 

Physics:-Version();

`The "Physics Updates" version in the MapleCloud is 1881 and is the same as the version installed in this computer, created 2025, October 7, 16:4 hours Pacific Time.`

> 

SupportTools:-Version();

`The Customer Support Updates version in the MapleCloud is 29 and is the same as the version installed in this computer, created June 23, 2025, 10:25 hours Eastern Time.`

> 

 

Example fail when using _EnvAllSolutions := true:

 
> 

restart;

> 

kernelopts('assertlevel'=2):

> 

ode:=diff(y(x),x) = ln(1+y(x)^2);
IC:=y(0)=0;
x0:=0;
sol:=y(x) = -sqrt(-1 + exp(RootOf(-Intat(-1/(2*tau*sqrt(-1 + exp(tau))*exp(-tau)), tau = _Z) + x + _C2)));

eq:=0=eval(rhs(sol),x=x0);
_EnvAllSolutions := true:
_EnvExplicit := true:
sol_C:=_C2=solve(eq,_C2);
sol:=eval(sol,sol_C);
odetest(%,[ode,IC])

diff(y(x), x) = ln(1+y(x)^2)

y(0) = 0

0

y(x) = -(-1+exp(RootOf(-Intat(-(1/2)/(tau*(-1+exp(tau))^(1/2)*exp(-tau)), tau = _Z)+x+_C2)))^(1/2)

0 = -(-1+exp(RootOf(-Intat(-(1/2)/(tau*(-1+exp(tau))^(1/2)*exp(-tau)), tau = _Z)+_C2)))^(1/2)

_C2 = Intat(-(1/2)*exp(tau)/(tau*(-1+exp(tau))^(1/2)), tau = (2*I)*Pi*_Z1)

y(x) = -(-1+exp(RootOf(-Intat(-(1/2)/(tau*(-1+exp(tau))^(1/2)*exp(-tau)), tau = _Z)+x+Intat(-(1/2)*exp(tau)/(tau*(-1+exp(tau))^(1/2)), tau = (2*I)*Pi*_Z1))))^(1/2)

Error, (in series/csgn) assertion failed

> 

 

Example Works  when using _EnvAllSolutions := false:

 
> 

restart;

> 

kernelopts('assertlevel'=2):

> 

ode:=diff(y(x),x) = ln(1+y(x)^2);
IC:=y(0)=0;
x0:=0;
sol:=y(x) = -sqrt(-1 + exp(RootOf(-Intat(-1/(2*tau*sqrt(-1 + exp(tau))*exp(-tau)), tau = _Z) + x + _C2)));

eq:=0=eval(rhs(sol),x=x0);
_EnvAllSolutions := false:
_EnvExplicit := true:
sol_C:=_C2=solve(eq,_C2);
sol:=eval(sol,sol_C);
odetest(%,[ode,IC])

diff(y(x), x) = ln(1+y(x)^2)

y(0) = 0

0

y(x) = -(-1+exp(RootOf(-Intat(-(1/2)/(tau*(-1+exp(tau))^(1/2)*exp(-tau)), tau = _Z)+x+_C2)))^(1/2)

0 = -(-1+exp(RootOf(-Intat(-(1/2)/(tau*(-1+exp(tau))^(1/2)*exp(-tau)), tau = _Z)+_C2)))^(1/2)

_C2 = Intat(-(1/2)*exp(tau)/(tau*(-1+exp(tau))^(1/2)), tau = 0)

y(x) = -(-1+exp(RootOf(-Intat(-(1/2)/(tau*(-1+exp(tau))^(1/2)*exp(-tau)), tau = _Z)+x+Intat(-(1/2)*exp(tau)/(tau*(-1+exp(tau))^(1/2)), tau = 0))))^(1/2)

[RootOf(Intat(exp(tau)/(tau*(-1+exp(tau))^(1/2)), tau = _Z)+2*x-Intat(exp(tau)/(tau*(-1+exp(tau))^(1/2)), tau = 0))-ln(exp(RootOf(Intat(exp(tau)/(tau*(-1+exp(tau))^(1/2)), tau = _Z)+2*x-Intat(exp(tau)/(tau*(-1+exp(tau))^(1/2)), tau = 0)))), 0]
 

 

 

 

Download odetest_fail_when_using_envAllsol_maple_2025_1_oct_21_2025.mw

are c__1 and _C1 no longer same object i...

nm 11558 Maple 2025
ode dsolve differential-equations
October 19 2025
2 0

The nice addition added to Maple 2022 in this  post made it clear that c__1 and _C1 are the same under the cover.

But then why in Maple 2025.1 it does not give this?

I found this when I was trying to find constants of integrations in solution of an ode, and used 

                 indets(sol,And(symbol, suffixed(_C, nonnegint))); 

Which did not find the constants of integration, since I happened to have typed the solution using c__1 and not _C1, but I thought they are the same.

Did something change or I still dont understand well the difference between c__1 and _C1 ?

Worksheet below.

> 

interface(version);

`Standard Worksheet Interface, Maple 2025.1, Linux, June 12 2025 Build ID 1932578`

> 

SupportTools:-Version();

`The Customer Support Updates version in the MapleCloud is 29 and is the same as the version installed in this computer, created June 23, 2025, 10:25 hours Eastern Time.`

> 

Physics:-Version();

`The "Physics Updates" version in the MapleCloud is 1881 and is the same as the version installed in this computer, created 2025, October 7, 16:4 hours Pacific Time.`

> 

restart;
> 

sol:= y(x)=-cos(x)/2+sin(x)/2+c__1*exp(-x);
indets(sol,And(symbol, suffixed(_C, nonnegint)));

y(x) = -(1/2)*cos(x)+(1/2)*sin(x)+c__1*exp(-x)

{}

> 

sol:= y(x)=-cos(x)/2+sin(x)/2+c__1*exp(-x);
indets(sol,And(symbol, suffixed(c__, nonnegint)));

y(x) = -(1/2)*cos(x)+(1/2)*sin(x)+c__1*exp(-x)

{c__1}

> 

sol:= y(x)=-cos(x)/2+sin(x)/2+_C1*exp(-x);
indets(sol,And(symbol, suffixed(c__, nonnegint)));

y(x) = -(1/2)*cos(x)+(1/2)*sin(x)+_C1*exp(-x)

{}

> 

sol:= y(x)=-cos(x)/2+sin(x)/2+_C1*exp(-x);
indets(sol,And(symbol, suffixed(_C, nonnegint)));

y(x) = -(1/2)*cos(x)+(1/2)*sin(x)+_C1*exp(-x)

{_C1}

> 

c__1 - _C1

c__1-_C1

> 

addressof(c__1);

36893628553737883996

> 

addressof(_C1);

36893628553623934140

Download why_c1_and_C1_not_same_oct_19_2025.mw

Update

Found out why. This only works if one calls dsolve() first.  Here is an example

> 

sol:=dsolve(diff(y(x),x)=x)

y(x) = (1/2)*x^2+c__1

> 

c__1 - _C1;

0

> 

indets(sol,And(symbol, suffixed(_C, nonnegint)));

{c__1}

> 

restart;
> 

my_sol:=y(x)=(x^2)/2+c__1;

y(x) = (1/2)*x^2+c__1

> 

c__1 - _C1;

c__1-_C1

> 

indets(my_sol,And(symbol, suffixed(_C, nonnegint)));

{}

 

 

Download why_c1_and_C1_not_same_oct_19_2025_V1.mw

But this is really confusing. c__1 before calling dsolve is not the same as c__1 after calling dsolve.

It will be better if Maple is changed such that these work the same all the time without having to call dsolve() first.

what is correct way to call a method in ...

nm 11558 Maple 2025
method object
October 17 2025
1 1

Maple help does not have an example I could find showing the right way to call method, which is meant to be called only from the constructor the object, before the object is fully build.

Help page does not have such example.

This worksheet shows 3 possible ways to do this. All seem to work fine. I am sure one can come up with more variations.

The question is, which one of these calls is the "right" way?

The method called from the constructor in this example is called process_age().

If someone knows an official Maple documentation showing one example of calling  a proc from constructor that will also help.

Version 1

 
> 

restart;

> 

module person()
   option object;

   local _name::string;
   local _age::posint;

   export ModuleCopy::static := proc( _self, proto::person,
        name::string,age::posint,$)
        _name:=name;
        _age:=process_age(age);
   end proc;

   local process_age:=proc(age::posint,$)::posint;
         age+1;
   end proc;

   export get_age::static:=proc(_self,$)::posint;
          _age;
   end proc;
end module;

module person () local _name::string, _age::posint, process_age; option object; end module

> 

o:=Object(person,"me",99);
o:-get_age()

module person () local _name::string, _age::posint, process_age; option object; end module

100
 

 

Version 2

 
> 

restart;

> 

module person()
   option object;

   local _name::string;
   local _age::posint;

   export ModuleCopy::static := proc( _self, proto::person,
        name::string,age::posint,$)
        _name:=name;
        _age:=process_age(age);
   end proc;

   local process_age::static:=proc(age::posint,$)::posint;
         age+1;
   end proc;

   export get_age::static:=proc(_self,$)::posint;
          _age;
   end proc;
end module;

module person () local _name::string, _age::posint; option object; end module

> 

 

> 

o:=Object(person,"me",99);
o:-get_age()

module person () local _name::string, _age::posint; option object; end module

100
 

 

Version 3

 
> 

restart;

> 

module person()
   option object;

   local _name::string;
   local _age::posint;

   export ModuleCopy::static := proc( _self, proto::person,
        name::string,age::posint,$)
        _name:=name;
        _age:=_self:-process_age(age);
   end proc;

   local process_age::static:=proc(_self,age::posint,$)::posint;
         age+1;
   end proc;

   export get_age::static:=proc(_self,$)::posint;
          _age;
   end proc;
end module;

module person () local _name::string, _age::posint; option object; end module

 

 

> 

o:=Object(person,"me",99);
o:-get_age()

module person () local _name::string, _age::posint; option object; end module

100
 

 

Download correct_way_to_call_method_from_constructor_oct_17_2025.mw

when to use 'specfunc(anything,y)...

nm 11558 Maple 2025
type specfunc
October 17 2025
1 0

Help page for structured types shows examples where they add delayed quotes around things. For example

So I started writing  'specfunc(anything,y)' instead of just  specfunc(anything,y). Only to find this breaks things when used inside a proc.

Here is an example.

> 

restart;
> 

#here it worksheetdir
IC:=y(x)=0;
indets(IC,'specfunc(anything,y)');      

y(x) = 0

{y(x)}

> 

#inside proc, same code fail
foo:=proc(func::function(name),IC::`=`)
    local y::symbol:=op(0,func);
    indets(IC,'specfunc(anything,y)');
end proc:
 
> 

foo(y(x),y(x)=0)

{}

 

 

Removing the quotes, it now works

> 

restart;
> 

#here it worksheetdir
IC:=y(x)=0;
indets(IC,'specfunc(anything,y)');      

y(x) = 0

{y(x)}

> 

#inside proc, same code fail
foo:=proc(func::function(name),IC::`=`)
    local y::symbol:=op(0,func);
    indets(IC,specfunc(anything,y));
end proc:
 
> 

foo(y(x),y(x)=0)

{y(x)}

 

 

Download delayed_vs_not_v2.mw

Download delayed_vs_not.mw

It took me 2 hrs debugging to find this, as when I copied code which was working in my worksheet to my function, it stopped working and did not know why.

So for now, I will not use quotes around specfunc or any others like the help page shows in its examples.

Is there a rule of thumb to follow here? The help page is very inconsistent. It shows some examples with quotes around and some without. Makes it hard to know why and when to add the delayed quotes. It seems arbitrary.

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