# Question:why infolevel stops working second time on some ode's?

## Question:why infolevel stops working second time on some ode's?

Maple 2023

I wonder if this a bug or Am I overlooking something?

I set infolevel[dsolve]:=5; and first time calling dsolve(ode), it works as expected. It prints on the screen the trace and steps it did.  But when I repeat the command dsolve, now it only prints one line and the rest of info that were printed before no longer show.

Should not the same information be printed each time? This is what happens on another example I tried. It seems infolevel does not work the same depending on the ode being solved?  Here is a worksheet attached to show the above.

Is there a workaround to make it display same information each time?

Maple 2023.2 on windows 10.

 >
 > restart;

 > interface(version);

 > ode:=[2*diff(x(t),t)+diff(y(t),t)=x(t)+y(t)+t,diff(x(t),t)+diff(y(t),t)=2*x(t)+3*y(t)+exp(t)]; infolevel[dsolve]:=5; dsolve(ode);

-> Solving each unknown as a function of the next ones using the order: [y(t), x(t)]

-> Calling odsolve with the ODE diff(diff(y(x) x) x) = 4*(diff(y(x) x))-y(x)-3*x+1 y(x) singsol = none

Methods for second order ODEs:

--- Trying classification methods ---

trying high order exact linear fully integrable

trying differential order: 2; linear nonhomogeneous with symmetry [0,1]

trying a double symmetry of the form [xi=0, eta=F(x)]

-> Try solving first the homogeneous part of the ODE

checking if the LODE has constant coefficients

<- constant coefficients successful

-> Determining now a particular solution to the non-homogeneous ODE

trying a rational particular solution

<- rational particular solution successful

<- solving first the homogeneous part of the ODE successful

 > dsolve(ode);

-> Solving each unknown as a function of the next ones using the order: [y(t), x(t)]

 > infolevel[dsolve]:=5;

 > dsolve(ode);

-> Solving each unknown as a function of the next ones using the order: [y(t), x(t)]

 > dsolve(ode);

-> Solving each unknown as a function of the next ones using the order: [y(t), x(t)]

 > ode:=diff(y(x),x\$2)+y(x)=sin(x); dsolve(ode);

Methods for second order ODEs:

--- Trying classification methods ---

trying high order exact linear fully integrable

trying differential order: 2; linear nonhomogeneous with symmetry [0,1]

trying a double symmetry of the form [xi=0, eta=F(x)]

-> Try solving first the homogeneous part of the ODE

checking if the LODE has constant coefficients

<- constant coefficients successful

-> Determining now a particular solution to the non-homogeneous ODE

building a particular solution using variation of parameters

<- solving first the homogeneous part of the ODE successful

 > dsolve(ode);

Methods for second order ODEs:

--- Trying classification methods ---

trying high order exact linear fully integrable

trying differential order: 2; linear nonhomogeneous with symmetry [0,1]

trying a double symmetry of the form [xi=0, eta=F(x)]

-> Try solving first the homogeneous part of the ODE

checking if the LODE has constant coefficients

<- constant coefficients successful

-> Determining now a particular solution to the non-homogeneous ODE

building a particular solution using variation of parameters

<- solving first the homogeneous part of the ODE successful

 >

On a side note. the first line of the display is hard to read. Any one know what it is supposed to mean by the space between the 1 and y(x) at the end there?

Another example where infolevel changes on second call to dsolve: The first call gives more information which is lost in the second call. There does not seem to be a way to fix this at user level.

 > restart;

 > ode:=diff(y(x),x)+(a*x+y(x))*y(x)^2=0: infolevel[dsolve]:=5: dsolve(ode)

Methods for first order ODEs:

--- Trying classification methods ---

trying 1st order linear

trying Bernoulli

trying separable

trying inverse linear

trying homogeneous types:

trying Chini

differential order: 1; looking for linear symmetries

trying exact

trying Abel

The relative invariant s3 is: -1/27*a*(2*a^2*x^3-9)

The first absolute invariant s5^3/s3^5 is: 729*a^4*x^6*(2*a^2*x^3-15)^3/(2*a^2*x^3-9)^5

The second absolute invariant s3*s7/s5^2 is: 5/3/a^2*(2*a^2*x^3-9)/x^3*(2*a^4*x^6-21*a^2*x^3+18)/(2*a^2*x^3-15)^2

...checking Abel class AIL (45)

...checking Abel class AIL (310)

...checking Abel class AIR (36)

inverse of the transformation solving the problem is: {t = 1/2*(-2*a^2)^(1/3)*x, u(t) = -(-2*a^2)^(1/3)/a*y(x)}

<- Abel successful

 > dsolve(ode)

Methods for first order ODEs:

--- Trying classification methods ---

trying 1st order linear

trying Bernoulli

trying separable

trying inverse linear

trying homogeneous types:

trying Chini

differential order: 1; looking for linear symmetries

trying exact

trying Abel

<- Abel successful

 >