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why odetest sometimes works and sometime...

Asked: nm 11373 Product: Maple 2024

January 09 2025

3 14

Is there something one can do to make Maple give same result each time? It seems all random.

Calling odetest sometimes gives internal error.

Error, (in trig/normal/sincosargs) too many levels of recursion

But it is random when and how it happens. Worksheet below shows that sometimes when adding infolevel[odetest]:=5; make the error go away. sometimes trying 2 or 3 times also makes the error go away.

This makes it impossible to reason about things, as sometimes I get different result using same exact code.

Is there something one can do to remove this internal error? Why it happens sometimes only? Do I need to clear something before calling odetest to make sure same result is obtained each time?

>	interface(version);

>	Physics:-Version();

>

libname;

$"C:\Users\Owner\maple\toolbox\2024\Physics Updates\lib", "C:\Program Files\Maple 2024\lib"$

>

restart;

>	sol:=y(x) = 1/2x(-1-(1+I3^(1/2))((I2^(1/2)-1+I)(I2^(1/2)+1+I)^2)^(2/3)-2((I* 2^(1/2)-1+I)(I2^(1/2)+1+I)^2)^(1/3)-I((I2^(1/2)+I)^2-1)3^(1/2)+(I2^(1/2)+ I)^2)/((I2^(1/2)-1+I)(I2^(1/2)+1+I)^2)^(1/3)/(I2^(1/2)+I); ode:=x^3+3xy(x)^2+(y(x)^3+3x^2y(x))*diff(y(x),x) = 0

y(x) = (1/2)*x*(-1-(1+I*3^(1/2))*((I*2^(1/2)+(-1+I))*(I*2^(1/2)+1+I)^2)^(2/3)-2*((I*2^(1/2)+(-1+I))*(I*2^(1/2)+1+I)^2)^(1/3)-I*((I*2^(1/2)+I)^2-1)*3^(1/2)+(I*2^(1/2)+I)^2)/(((I*2^(1/2)+(-1+I))*(I*2^(1/2)+1+I)^2)^(1/3)*(I*2^(1/2)+I))

>	odetest(sol,ode,y(x));

Error, (in trig/normal/sincosargs) too many levels of recursion

>	odetest(sol,ode);

Error, (in trig/normal/sincosargs) too many levels of recursion

>	infolevel[odetest]:=5;

>	odetest(sol,ode);

odetest: Performing an implicit solution test

odetest: Performing an explicit (try hard) solution test

odetest: Performing an implicit solution (II) test

odetest: Performing another explicit (try soft) solution test

>	odetest(sol,ode,y(x));

odetest: Performing an implicit solution test

odetest: Performing an explicit (try hard) solution test

odetest: Performing an implicit solution (II) test

odetest: Performing another explicit (try soft) solution test

>	infolevel[odetest]:=0;

>	odetest(sol,ode,y(x));

>

restart;

>	sol:=y(x) = 1/2x(-1-(1+I3^(1/2))((I2^(1/2)-1+I)(I2^(1/2)+1+I)^2)^(2/3)-2((I* 2^(1/2)-1+I)(I2^(1/2)+1+I)^2)^(1/3)-I((I2^(1/2)+I)^2-1)3^(1/2)+(I2^(1/2)+ I)^2)/((I2^(1/2)-1+I)(I2^(1/2)+1+I)^2)^(1/3)/(I2^(1/2)+I); ode:=x^3+3xy(x)^2+(y(x)^3+3x^2y(x))*diff(y(x),x) = 0

y(x) = (1/2)*x*(-1-(1+I*3^(1/2))*((I*2^(1/2)+(-1+I))*(I*2^(1/2)+1+I)^2)^(2/3)-2*((I*2^(1/2)+(-1+I))*(I*2^(1/2)+1+I)^2)^(1/3)-I*((I*2^(1/2)+I)^2-1)*3^(1/2)+(I*2^(1/2)+I)^2)/(((I*2^(1/2)+(-1+I))*(I*2^(1/2)+1+I)^2)^(1/3)*(I*2^(1/2)+I))

>	odetest(sol,ode,y(x));

Error, (in trig/normal/sincosargs) too many levels of recursion

>	odetest(sol,ode,y(x));

Error, (in trig/normal/sincosargs) too many levels of recursion

>	odetest(sol,ode,y(x));

Download why_odetest_sometimes_fail_internal.mw

Add tracelast; after an error gives long output with this at end

...
#(\`trig/normal\`,8): sincosargs := [\`trig/normal/sincosargs\`(a)];
 \`trig/normal/sincosargs\` called with arguments: ((-2472*2^(1/2)+3496)*3^(1/2)-4288*2^(1/2)+6064)*(10+7*2^(1/2))^(1/2)+(6008*6^(1/2)-8496*3^(1/2)+10408*2^(1/2)-14720)*cos((1/24)*Pi)
 #(\`trig/normal/sincosargs\`,2): return op(map(procname,{op(x)}))
 \`trig/normal/sincosargs\` called with arguments: ((-2472*2^(1/2)+3496)*3^(1/2)-4288*2^(1/2)+6064)*(10+7*2^(1/2))^(1/2)
 #(\`trig/normal/sincosargs\`,2): return op(map(procname,{op(x)}))
 \`trig/normal/sincosargs\` called with arguments: (-2472*2^(1/2)+3496)*3^(1/2)-4288*2^(1/2)+6064
 #(\`trig/normal/sincosargs\`,2): return op(map(procname,{op(x)}))
 \`trig/normal/sincosargs\` called with arguments: (-2472*2^(1/2)+3496)*3^(1/2)
 #(\`trig/normal/sincosargs\`,2): return op(map(procname,{op(x)}))
 \`trig/normal/sincosargs\` called with arguments: -2472*2^(1/2)+3496
 #(\`trig/normal/sincosargs\`,2): return op(map(procname,{op(x)}))
 \`trig/normal/sincosargs\` called with arguments: -2472*2^(1/2)
 #(\`trig/normal/sincosargs\`,2): return op(map(procname,{op(x)}))

Not only is it random error, it also can not be cought using try/catch. So the whole program now stop and there is no way around it. If it was at least possible to trap the error, then it will not be a big deal. But when not even possible to trap Maple errors, then what is one to do?

Update Jan 18, 2025

I did not want to make new post on this, even though the error is different, but it is similar issue to this post.

I found another example of this random failure of odetest using same input. May be this will help Maplesoft find the cause.

The internal error this time is Error, (in depends) too many levels of recursion

In this worksheet below. the same ode and 3 solutions were used. As you see, sometimes odetest do not generate internal error, and sometimes it does. All happen on 3rd call to odetest.

So it is completely random why this happen. The first and 4ht tries generate no error, but the second and the third do. All were run after restart is called. So one would expect same output from each try,

>

restart;

>	interface(version); Physics:-Version();

First Try

>

ode:=1+y(x)^2+(x-exp(-arctan(y(x))))*diff(y(x),x) = 0;
sol_1:=y(x) = -tan(LambertW(-x/exp(_C1))+_C1);
timelimit(30,odetest(sol_1,ode,y(x)));

sol_2:=x*exp(arctan(y(x)))-arctan(y(x)) = _C1;
timelimit(30,odetest(sol_2,ode,y(x)));

sol_3:=y(x) = tan(-LambertW(-x*exp(_C2))+_C2);
timelimit(30,odetest(sol_3,ode,y(x)));

Error, (in depends) too many levels of recursion

Second Try

>

restart;

>

ode:=1+y(x)^2+(x-exp(-arctan(y(x))))*diff(y(x),x) = 0;
sol_1:=y(x) = -tan(LambertW(-x/exp(_C1))+_C1);
timelimit(30,odetest(sol_1,ode,y(x)));

sol_2:=x*exp(arctan(y(x)))-arctan(y(x)) = _C1;
timelimit(30,odetest(sol_2,ode,y(x)));

sol_3:=y(x) = tan(-LambertW(-x*exp(_C2))+_C2);
timelimit(30,odetest(sol_3,ode,y(x)));

>

Third Try

>

restart;

>

ode:=1+y(x)^2+(x-exp(-arctan(y(x))))*diff(y(x),x) = 0;
sol_1:=y(x) = -tan(LambertW(-x/exp(_C1))+_C1);
timelimit(30,odetest(sol_1,ode,y(x)));

sol_2:=x*exp(arctan(y(x)))-arctan(y(x)) = _C1;
timelimit(30,odetest(sol_2,ode,y(x)));

sol_3:=y(x) = tan(-LambertW(-x*exp(_C2))+_C2);
timelimit(30,odetest(sol_3,ode,y(x)));

Error, (in depends) too many levels of recursion

>

4th Try

>

restart;

>

ode:=1+y(x)^2+(x-exp(-arctan(y(x))))*diff(y(x),x) = 0;
sol_1:=y(x) = -tan(LambertW(-x/exp(_C1))+_C1);
timelimit(30,odetest(sol_1,ode,y(x)));

sol_2:=x*exp(arctan(y(x)))-arctan(y(x)) = _C1;
timelimit(30,odetest(sol_2,ode,y(x)));

sol_3:=y(x) = tan(-LambertW(-x*exp(_C2))+_C2);
timelimit(30,odetest(sol_3,ode,y(x)));

>

Download bug_odetest_jan_18_2025.mw

replacing derivatives with symbol^order...

Asked: nm 11373 Product: Maple

January 06 2025

1 1

sometimes I need to check if an ode is missing y(x) or not. Since diff(y(x),x) has y(x) in it, then can not just check if the ode has y(x) or not as is, as this will always gives true if diffy(y(x),x) is there of any order.

Currently what I do, is change all y',y'',y''', etc... to Z,Z^2,Z^3,etc... and then after that it is safe to check if y(x) exist or not.

Is there a better way to do this? Below is what I currently do and it works. Just wondering if there could a more elgent way to do this.

Download find_if_any_ode_has_yx_jan_6_2025.mw

How to increase or decrease number of ar...

Asked: nm 11373 Product: Maple 2024

January 04 2025

3 4

For plotting phase plot of two system of equations (autonomous), is there an option to increase of reduce number of arrows/line drawn? I am not able to find such an option from help.

Below is an example. Google AI says stepsize should change the number of arrows, but it does not. It had no effect. Below is worksheet showing one example where I like to reduce number of arrows (not the size of the arrow, which is set to medium now).

I also tried numpoints option and it had no effect of how many arrows are drawn

Download change_number_of_arrows_jan_4_2025.mw

For reference, I'd like to do something similar using another system as below where it has option to change number of arrows.

Physics update date mismatch...

Asked: nm 11373 Product: Maple 2024

January 02 2025

1 0

something I always wondered about. On Maple website it says

Notice the date above., December 26.

On my Maple, with latest update, same version is printed, but the date is way off.

It says December 2, not 26.

Why is that? Should not the date be the same sicne same version 1840 of Physics update?

Download physics_version.mw

Bug report: Error, (in dsolve) invalid s...

Asked: nm 11373 Product: Maple 2024

December 27 2024

0 2

I do not remember if I reported this before or not. Can't find it. Just in case, I am posting this.

If someone find it is duplicate, feel free to delete this. But this is in latest Maple 2024.2. May be this can be fixed in time by Maple 2025 version.

>

restart;

>	interface(version);

>	Physics:-Version();

>

libname;

$"C:\Users\Owner\maple\toolbox\2024\Physics Updates\lib", "C:\Program Files\Maple 2024\lib"$

>	ode := diff(y(x),x)/y(x)-(3(4x^2+y(x)^2+1))/(2x(4x^2+y(x)^2-2-2x))=0;

(diff(y(x), x))/y(x)-(3/2)*(4*x^2+y(x)^2+1)/(x*(4*x^2+y(x)^2-2-2*x)) = 0

>	DEtools:-odeadvisor(ode);

>	dsolve(ode,y(x));

Error, (in dsolve) invalid subscript selector

>

restart;

>	infolevel[dsolve]:=5;

>	ode := diff(y(x),x)/y(x)-(3(4x^2+y(x)^2+1))/(2x(4x^2+y(x)^2-2-2x))=0:

>	dsolve(ode,y(x));

Methods for first order ODEs:

--- Trying classification methods ---

trying a quadrature

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

Looking for potential symmetries

trying inverse_Riccati

trying an equivalence to an Abel ODE

equivalence obtained to this Abel ODE: diff(y(x),x) = 3/2*(4*x^2+1)/x/(2*x^2-x-1)*y(x)-(x^2+2*x+3)/x/(2*x^2-x-1)^2*y(x)^2+3/8*(2*x+3)/(2*x^2-x-1)^3/x*y(x)^3

trying to solve the Abel ODE ...

The relative invariant s3 is: -1/432*(8*x^4+40*x^3+45*x^2-270*x+135)/x^3/(x-1)^6/(2*x+1)^4

The first absolute invariant s5^3/s3^5 is: 729/16*(128*x^8+1152*x^7+3696*x^6+1744*x^5+8148*x^4-31500*x^3+6615*x^2-5670*x+8505)^3/(2*x+1)^4/(8*x^4+40*x^3+45*x^2-270*x+135)^5

The second absolute invariant s3*s7/s5^2 is: 1/3*(8*x^4+40*x^3+45*x^2-270*x+135)*(10240*x^12+133120*x^11+697600*x^10+1710080*x^9+3358592*x^8-1701568*x^7+6692592*x^6-18182448*x^5+2088072*x^4-7938000*x^3+2525985*x^2+1786050*x+2679075)/(128*x^8+1152*x^7+3696*x^6+1744*x^5+8148*x^4-31500*x^3+6615*x^2-5670*x+8505)^2

...checking Abel class AIL (45)

...checking Abel class AIL (310)

...checking Abel class AIR (36)

...checking Abel class AIL (301)

...checking Abel class AIL (1000)

...checking Abel class AIL (42)

...checking Abel class AIL (185)

...checking Abel class AIA (by Halphen)

...checking Abel class AIL (205)

...checking Abel class AIA (147)

...checking Abel class AIL (581)

...checking Abel class AIL (200)

...checking Abel class AIL (257)

...checking Abel class AIL (400)

...checking Abel class AIA (515)

...checking Abel class AIR (1001)

...checking Abel class AIA (201)

...checking Abel class AIA (815)

Looking for potential symmetries

... changing x -> 1/x, trying again

Looking for potential symmetries

The third absolute invariant s5*s7/s3^4 is: 243/16*(10240*x^12+133120*x^11+697600*x^10+1710080*x^9+3358592*x^8-1701568*x^7+6692592*x^6-18182448*x^5+2088072*x^4-7938000*x^3+2525985*x^2+1786050*x+2679075)/(2*x+1)^4*(128*x^8+1152*x^7+3696*x^6+1744*x^5+8148*x^4-31500*x^3+6615*x^2-5670*x+8505)/(8*x^4+40*x^3+45*x^2-270*x+135)^4

-> ======================================

-> ...checking Abel class D (by Appell)

-> Step 1: checking for a disqualifying factor on F after evaluating x at a number

Trying x = 2

*** No disqualifying factor on F was found ***

-> Step 2: calculating resultants to eliminate F and get candidates for C

*** Candidates for C are {4/27} ***

-> Step 3: looking for a solution F depending on x

*** No solution F of x was found ***

-> ======================================

-> ...checking Abel class B (by Liouville)

-> Step 1: checking for a disqualifying factor on F after evaluating x at a number

Trying x = 2

*** No disqualifying factor on F was found ***

-> Step 2: calculating resultants to eliminate F and get candidates for C

*** Candidates for C are {1, 4, 1/4} ***

-> Step 3: looking for a solution F depending on x

*** No solution F of x was found ***

-> ======================================

-> ...checking Abel class A (by Abel)

-> Step 1: checking for a disqualifying factor on F after evaluating x at a number

Trying x = 2

*** No disqualifying factor on F was found ***

-> Step 2: calculating resultants to eliminate F and get candidates for C

*** Candidates for C are {0, -1/4} ***

-> Step 3: looking for a solution F depending on x

*** No solution F of x was found ***

-> ======================================

-> ...checking Abel class C (by Abel)

-> Step 1: checking for a disqualifying factor on F after evaluating x at a number

Trying x = 2

*** No disqualifying factor on F was found ***

-> Step 2: calculating resultants to eliminate F and get candidates for C

*** Candidates for C are {2, -11676447873119/75975070592769, 9/5, 15632211369872/75439744512117, 46273613050865/52325357771027, 75312059745574/25138886548531} ***

-> Step 3: looking for a solution F depending on x

_____________________________

C = 9/5 leads to a useless solution (F does not depend on x)

*** No solution F of x was found ***

-> ======================================

-> ...checking Abel class AIL 1.6

-> Step 1: checking for a disqualifying factor on F after evaluating x at a number

Trying x = 2

*** No disqualifying factor on F was found ***

-> Step 2: calculating resultants to eliminate F and get candidates for C

*** Candidates for C are {-4, 16} ***

-> Step 3: looking for a solution F depending on x

*** No solution F of x was found ***

-> ======================================

-> ...checking Abel class AIL 1.8

-> Step 1: checking for a disqualifying factor on F after evaluating x at a number

Trying x = 2

*** No disqualifying factor on F was found ***

-> Step 2: calculating resultants to eliminate F and get candidates for C

*** Candidates for C are {0, -116457391291688/45108305127449, -96869842492381/35485755507516, -36964550865207/94238117721032, -32286830321303/11596568583712, 32286830321303/11596568583712, 36964550865207/94238117721032, 96869842492381/35485755507516, 116457391291688/45108305127449} ***

-> Step 3: looking for a solution F depending on x

*** No solution F of x was found ***

-> ======================================

-> ...checking Abel class AIL 1.9

-> Step 1: checking for a disqualifying factor on F after evaluating x at a number

Trying x = 2

*** No disqualifying factor on F was found ***

-> Step 2: calculating resultants to eliminate F and get candidates for C

*** Candidates for C are {-2/9, -1/9} ***

-> Step 3: looking for a solution F depending on x

*** No solution F of x was found ***

-> ======================================

-> ...checking Abel class AIA 1.51

-> Step 1: checking for a disqualifying factor on F after evaluating x at a number

Trying x = 2

*** No disqualifying factor on F was found ***

-> Step 2: calculating resultants to eliminate F and get candidates for C

*** Candidates for C are {0, -94917840318055/84247876515289, -85939756880989/51399391393709, -82210125508529/36853933366676, -74381886667083/82545981233858, -41168492684238/33804146399567, -15658703496425/19275443365317, -9175348901453/101481647952193, 3/4, 15/4, 5568553686203/113599855351490, 12774469621703/63437040534358, 17836021821409/102823494563886, 39657708622139/74009717243016, 82495450887526/27663991325651, 86656182727564/45157560524183, 90074893410229/54954593917906, 100200889070747/32282555481919, 113612565327585/103754255779069} ***

-> Step 3: looking for a solution F depending on x

_____________________________

C = 15/4 leads to a useless solution (F does not depend on x)

*** No solution F of x was found ***

-> ======================================

-> ...checking Abel class AIA 1.5

-> Step 1: checking for a disqualifying factor on F after evaluating x at a number

Trying x = 2

*** No disqualifying factor on F was found ***

-> Step 2: calculating resultants to eliminate F and get candidates for C

*** Candidates for C are {-1, 1, -113553630998996/78694251194667, -112790344818825/35834119404842, -104905620984375/18860524785743, -95409943222181/78810323073434, -77648002983645/31218435062578, -67259194033608/9576982470445, -46892223838816/86694928762723, -45901561561111/29768419326991, -34674701564566/6522678435631, 26154715634141/21099761863911, 42841215778132/81925179545457, 52638927823233/15127919203723, 54069389554571/5444364811188, 54445812264368/10328928623117, 56815569067370/40738034746481, 75614540760757/62881656939350, 76459718737483/64786816765621, 85896394925571/88677987470966, 90623073438172/24246571690325, 103628692054633/17857341616628, 117754725919014/60191028908095} ***

-> Step 3: looking for a solution F depending on x

_____________________________

C = -1 leads to a useless solution (F does not depend on x)

_____________________________

C = -113553630998996/78694251194667 leads to a useless solution (F does not depend on x)

_____________________________

C = -112790344818825/35834119404842 leads to a useless solution (F does not depend on x)

_____________________________

C = -104905620984375/18860524785743 leads to a useless solution (F does not depend on x)

_____________________________

C = -95409943222181/78810323073434 leads to a useless solution (F does not depend on x)

_____________________________

C = -77648002983645/31218435062578 leads to a useless solution (F does not depend on x)

_____________________________

C = -67259194033608/9576982470445 leads to a useless solution (F does not depend on x)

_____________________________

C = -46892223838816/86694928762723 leads to a useless solution (F does not depend on x)

_____________________________

C = -45901561561111/29768419326991 leads to a useless solution (F does not depend on x)

_____________________________

C = -34674701564566/6522678435631 leads to a useless solution (F does not depend on x)

_____________________________

C = 26154715634141/21099761863911 leads to a useless solution (F does not depend on x)

_____________________________

C = 42841215778132/81925179545457 leads to a useless solution (F does not depend on x)

_____________________________

C = 52638927823233/15127919203723 leads to a useless solution (F does not depend on x)

_____________________________

C = 54069389554571/5444364811188 leads to a useless solution (F does not depend on x)

_____________________________

C = 54445812264368/10328928623117 leads to a useless solution (F does not depend on x)

_____________________________

C = 56815569067370/40738034746481 leads to a useless solution (F does not depend on x)

_____________________________

C = 75614540760757/62881656939350 leads to a useless solution (F does not depend on x)

_____________________________

C = 76459718737483/64786816765621 leads to a useless solution (F does not depend on x)

_____________________________

C = 85896394925571/88677987470966 leads to a useless solution (F does not depend on x)

_____________________________

C = 90623073438172/24246571690325 leads to a useless solution (F does not depend on x)

_____________________________

C = 103628692054633/17857341616628 leads to a useless solution (F does not depend on x)

_____________________________

C = 117754725919014/60191028908095 leads to a useless solution (F does not depend on x)

*** No solution F of x was found ***

-> ======================================

-> ...checking Abel class AIA 1.52

-> Step 1: checking for a disqualifying factor on F after evaluating x at a number

Trying x = 2

*** No disqualifying factor on F was found ***

-> Step 2: calculating resultants to eliminate F and get candidates for C

*** Candidates for C are {-5, -4, -3, 0, 1, 2, -3/2} ***

-> Step 3: looking for a solution F depending on x

*** No solution F of x was found ***

-> ======================================

-> ...checking Abel class AIA 1.53

-> Step 1: checking for a disqualifying factor on F after evaluating x at a number

Trying x = 2

*** No disqualifying factor on F was found ***

-> Step 2: calculating resultants to eliminate F and get candidates for C

*** Candidates for C are {-3, -1, 1, 2, -3/2, -2/3, -1/2} ***

-> Step 3: looking for a solution F depending on x

_____________________________

C = -3 leads to a useless solution (F does not depend on x)

_____________________________

C = -3/2 leads to a useless solution (F does not depend on x)

*** No solution F of x was found ***

trying to map the Abel into a solvable 2nd order ODE

...checking Abel class AIA 2-parameter, reducible to Riccati

Error, (in dsolve) invalid subscript selector

>

restart;

>	ode := diff(y(x),x)/y(x)-(3(4x^2+y(x)^2+1))/(2x(4x^2+y(x)^2-2-2x))=0:

>	dsolve(ode,y(x));

Error, (in dsolve) invalid subscript selector

>	tracelast;

Error, (in dsolve) invalid subscript selector

Download dsolve_invalid_subscript_dec_27_2024.mw

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why odetest sometimes works and sometime...

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