We have a few older problems that involve approximating difference quotient limits.
The problem works fine, but the solutions are now generating a non-fatal warning that never occurred in the past.
In the setup of the question, we introduce h as a variable:
Context()->variables->add(h => "Real");
We define a function $f and a non-zero random $a. The difference quotient is defined using
$diff = ($f->substitute(x=>"$a + x") - $f->eval(x=>$a))/x;
In the solution, we want to display the partially simplified difference quotient, and then the simplified version. We have a line like the following in a PGML solution:
The difference quotient [`\frac{f(a+h) - f(a)}{h}`] becomes [`[$diff->substitute(x=>h)->reduce()]`] which simplifies to [`[$simpl]+h`].
In the past this worked fine, but now we are getting the following warnings. It seems I can ignore them for now, but is there a way to fix this?
Non fatal warnings. These are only displayed for users with permission to view problem debugging info.Unquoted string "h" may clash with future reserved word at line 1 of (eval 8170)from within PGML::Eval called at line 937 of [PG]/macros/core/PGML.plfrom within PGML::Parse::replaceVariable called at line 898 of [PG]/macros/core/PGML.plfrom within PGML::Parse::stackText called at line 910 of [PG]/macros/core/PGML.plfrom within PGML::Parse::stackString called at line 783 of [PG]/macros/core/PGML.plfrom within PGML::Parse::terminateGetString called at line 261 of [PG]/macros/core/PGML.plfrom within PGML::Parse::Terminate called at line 159 of [PG]/macros/core/PGML.plfrom within PGML::Parse::Parse called at line 75 of [PG]/macros/core/PGML.plfrom within PGML::Parse::new called at line 1991 of [PG]/macros/core/PGML.plfrom within PGML::Format called at line 2009 of [PG]/macros/core/PGML.plfrom within PGML::Format2 called at line 112 of UlethMath/Calculus/01-Limits/1-Introduction/calc01118.pg