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Question: What can cause Physics to be activated when one is not making Physics:- calls explicitly?

Question:What can cause Physics to be activated when one is not making Physics:- calls explicitly?

nm 11538 Maple 2025
diff convert physics
2 hours ago
0

In 2025.2, I found that calling Physics:-Setup causes code of `convert/diff` to change (on the fly) causing error.

I removed from my code the places I was calling Physics:-Setup explicitly, but the error still shows up. Which means there is still places in the code to cause Physics to come into play.

I just installed 2025.2 and have not done anything yet. Just running a test. 

Does one need to install Physics package?

First, let me give an example showing that calling Physics:-Setup changes `convert/diff` which ends up causing an internal Maple error

> 

interface(version);

`Standard Worksheet Interface, Maple 2025.2, Windows 10, November 11 2025 Build ID 1971053`

> 

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" package is not available for the version of Maple under development`

> 

restart;

Original result. No problem

 
> 

print(`convert/diff`);

proc (a, { useeval::truefalse := false }) local ee, zD; ee := `PDEtools/usediff`(a); zD := indets(ee, 'And(function, satisfies(proc (f) options operator, arrow; (op(0, f))::`PDEtools/D/structure` end proc))'); if zD = {} then ee else _Env_t_in_use := `tools/get_symbols`(a); if useeval then zD := map(`convert/diff/D_to_eval@diff`, zD, ':-useEval'); zD := map(proc (u) options operator, arrow; lhs(u) = subsop(0 = eval, rhs(u)) end proc, zD); subs(zD, ee) else subs(map(`convert/diff/D_to_eval@diff`, zD), a) end if end if end proc

> 

T:=D(x)(infinity):

> 

PDEtools:-difforder(convert(T,diff))

1

 

 

 

After call Physics:-Setup

 
> 

restart;

> 

Physics:-Setup('assumingusesAssume' = false):

> 

print(`convert/diff`);

proc () local ans; ans := usepdiff(args); if has([ans], 'D') then ans := Physics:-OriginalValue["convert/diff"](ans, args[2 .. -1]) end if; ans end proc

> 

T:=D(x)(infinity):

> 

PDEtools:-difforder(convert(T,diff))

Error, (in unknown) invalid input: diff received infinity, which is not valid for its 2nd argument

 

 

 

 

Download why_code_changes_calling_Physics_maple_2025_2_nov_24_2025.mw

Notice that now calling PDEtools:-difforder(convert(T,diff))  fail because Physics:- was called.

But my code now has no calls to Physics:-, I made sure to comment all those out. 

But I still get same error when I run my test program. Not able to find where Physics is "activated" again to cause the code change in `convert/diff` that happens dynamically when Physics is loaded.

It must be happining on different call internally. But have no idea why and where.

This is all on new PC. I have no Maple ini files or anything like this that can cause this.

Will installing Physics package explicity fixes this?   
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