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Question: solve failing on second time called.

Question:solve failing on second time called.

nm 11353 Maple 2025
solve assuming physics
May 28 2025
2

I've been debugging this for 20 hrs and finally able to make an example.

I noticed that solve() suddenly no longer works and times out.

First time calling solve() works. Second time it I see message

               Warning, solve may be ignoring assumptions on the input variables.

And it hangs.  Same exact code.   It has to do with calling odetest before and using Physics:-Setup('assumingusesAssume' = false):

i.e. this works
  
     odetest(...) assuming integer
     solve(....) #no hang
     odetest(....) assuming positive

     odetest(...)  assuming integer
     solve(....)  #no hang

But this does not work

     odetest(...) assuming integer
     solve(....) #no hang
     Physics:-Setup('assumingusesAssume' = false):
     odetest(....) assuming positive
     Physics:-Setup('assumingusesAssume' = true):
     odetest(...) assuming integer
     solve(...)   #HANGS     

Here is worksheet showing the problem. If I remove first call to odetest, solve do not hang.

Also removing Physics:-Setup('assumingusesAssume' = false):, solve also works OK. (ie. does not hang)

So it has to do with some internal caching which causes solve to stop working.

Can others reproduce this and can cause it and how to fix it so solve do not hang second time?

The input used below is not important. It is just what I found to cause this. One would expect solve() to work same way for same input all the time.

Also, same problem happens when using PDEtools:-Solve instead of solve. It hangs second time.

> 

interface(version);

`Standard Worksheet Interface, Maple 2025.0, Linux, March 24 2025 Build ID 1909157`

> 

Physics:-Version();

`The "Physics Updates" version in the MapleCloud is 1873 and is the same as the version installed in this computer, created 2025, May 18, 21:44 hours Pacific Time.`

> 

SupportTools:-Version();

`The Customer Support Updates version in the MapleCloud is 20 and is the same as the version installed in this computer, created May 23, 2025, 23:34 hours Eastern Time.`

> 

restart

DEFINE input

 
> 

ode:=y(x)*sqrt(1 + diff(y(x), x)^2) - a*y(x)*diff(y(x), x) - a*x = 0:
sol:=-_C4^2 + (-y(x)*sqrt(_C4^2/y(x)^2) + a*x)^2/a^2 + y(x)^2 = 0:
ode_to_test:=y(x)*(1+diff(y(x),x)^2)^(1/2)-a*y(x)*diff(y(x),x)-a*x = 0:

FIRST TIME solve works

 
> 

    try
        timelimit(30,(odetest(sol,ode,y(x)) assuming integer));
    catch:
        NULL;
    end try:

    try
        timelimit(30,[solve(ode_to_test,diff(y(x),x))]);
        print("SOLVE worked");              
    catch:
        print("WHY TIMED OUT??");              
    end try:

    Physics:-Setup('assumingusesAssume' = false):
    try
        timelimit(30, (odetest(sol,ode,y(x)) assuming positive) );
    catch:
        NULL;
    end try:
    Physics:-Setup('assumingusesAssume' = true):

"SOLVE worked"

> 

 

> 

 

RUN SAME CODE AS ABOVE again, now it does not work

 
> 

    try
        timelimit(30,(odetest(sol,ode,y(x)) assuming integer));
    catch:
        NULL;
    end try:

    try
        timelimit(30,[solve(ode_to_test,diff(y(x),x))]);
        print("SOLVE worked");              
    catch:
        print("WHY TIMED OUT??");              
    end try:

    Physics:-Setup('assumingusesAssume' = false):
    try
        timelimit(30, (odetest(sol,ode,y(x)) assuming positive) );
    catch:
        NULL;
    end try:
    Physics:-Setup('assumingusesAssume' = true):

Warning, solve may be ignoring assumptions on the input variables.

"WHY TIMED OUT??"

 

 

 

 

Download why_solve_stops_working_maple_2025_may_28_2025.mw

This worksheet below shows that by removing Physics:-Setup('assumingusesAssume' = false): now solve works OK second time. (I turn on/off Physics:-Setup('assumingusesAssume' since I found sometimes it can help with odetest to turn it off in some other cases. But now I am scared of touching this setting as it seems to have side effects internally)

> 

interface(version);

`Standard Worksheet Interface, Maple 2025.0, Linux, March 24 2025 Build ID 1909157`

> 

Physics:-Version();

`The "Physics Updates" version in the MapleCloud is 1873 and is the same as the version installed in this computer, created 2025, May 18, 21:44 hours Pacific Time.`

> 

SupportTools:-Version();

`The Customer Support Updates version in the MapleCloud is 20 and is the same as the version installed in this computer, created May 23, 2025, 23:34 hours Eastern Time.`

> 

restart

DEFINE input

 
> 

ode:=y(x)*sqrt(1 + diff(y(x), x)^2) - a*y(x)*diff(y(x), x) - a*x = 0:
sol:=-_C4^2 + (-y(x)*sqrt(_C4^2/y(x)^2) + a*x)^2/a^2 + y(x)^2 = 0:
ode_to_test:=y(x)*(1+diff(y(x),x)^2)^(1/2)-a*y(x)*diff(y(x),x)-a*x = 0:

FIRST TIME solve works

 
> 

    try
        timelimit(30,(odetest(sol,ode,y(x)) assuming integer));
    catch:
        NULL;
    end try:

    try
        timelimit(30,[solve(ode_to_test,diff(y(x),x))]);
        print("SOLVE worked");              
    catch:
        print("WHY TIMED OUT??");              
    end try:

    try
        timelimit(30, (odetest(sol,ode,y(x)) assuming positive) );
    catch:
        NULL;
    end try:

"SOLVE worked"

> 

 

> 

 

RUN SAME CODE AS ABOVE again, now it does not work

 
> 

    try
        timelimit(30,(odetest(sol,ode,y(x)) assuming integer));
    catch:
        NULL;
    end try:

    try
        timelimit(30,[solve(ode_to_test,diff(y(x),x))]);
        print("SOLVE worked");              
    catch:
        print("WHY TIMED OUT??");              
    end try:

    try
        timelimit(30, (odetest(sol,ode,y(x)) assuming positive) );
    catch:
        NULL;
    end try:

"SOLVE worked"

 

 

 

 

Download why_solve_stops_working_maple_2025_may_28_2025_V2.mw
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