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Question: why setting warnlevel makes dsolve give different form of the solution?

Question:why setting warnlevel makes dsolve give different form of the solution?

nm 7580 Maple 2020
interface ode dsolve differential-equations
November 29 2020
2

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.
 

> 

restart;
> 

interface(version);

`Standard Worksheet Interface, Maple 2020.2, Windows 10, November 11 2020 Build ID 1502365`

> 

Physics:-Version();

`The "Physics Updates" version in the MapleCloud is 884 and is the same as the version installed in this computer, created 2020, November 25, 16:49 hours Pacific Time.`

> 

interface(warnlevel=0);

3

> 

ic:=y(0)=3:
ode := diff(y(x),x)*y(x)/(1+1/2*sqrt(1+diff(y(x),x)^2))=-x:
sol_1:=dsolve([ode,ic],y(x),singsol=all);

y(x) = -3+(1/3)*(-9*x^2+324)^(1/2), y(x) = 1+(1/3)*(-9*x^2+36)^(1/2)

> 

restart;
> 

ic:=y(0)=3:
ode := diff(y(x),x)*y(x)/(1+1/2*sqrt(1+diff(y(x),x)^2))=-x:
sol_2:=dsolve([ode,ic],y(x),singsol=all);

y(x) = -3+(-x^2+36)^(1/2), y(x) = 1+(-x^2+4)^(1/2)


 

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

 
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