[Maxima-commits] [git] Maxima CAS branch master updated. branch-5_49-base-571-g6f964815a

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- Log -----------------------------------------------------------------
commit 6f964815a3c43b118de53d80ee68ad54daf5c032
Author: Robert Dodier <rob...@so...>
Date:   Thu Jun 4 08:43:05 2026 -0700

    Package ezunits: call sublis instead of subst in the macro "dimensionally",
    which resolves a bug reported to maxima-discuss 2026-06-01, "Solving Equation with Ezunits Problem".
    
    sublist makes substitutions in parallel, while subst makes them in sequence;
    subst calls SIMPLIFYA between one substitution and the next.
    The result was that subst was creating an expression of the form (a`foo + b`bar)`baz
    which is handled incorrectly by "``" -- now the result is a`foo*baz + b`bar*baz,
    which is handled correctly.
    
    Another way to resolve this would be to make "`" distribute over "+" --
    might want to do that too. In any event, parallel substitution makes
    more sense than serial, since the substitutions are independent.

diff --git a/share/ezunits/ezunits_functions.mac b/share/ezunits/ezunits_functions.mac
index bf99a637a..2756f8dcf 100644
--- a/share/ezunits/ezunits_functions.mac
+++ b/share/ezunits/ezunits_functions.mac
@@ -642,8 +642,8 @@ dimensionally (e%) ::=
       units_gensyms : make_array ('hashed),
       unitless_args : applyb1 (e%_args, rununitify),
       reunitification_eqs : map (lambda ([e], lhs (e) = 1 ` rhs (e)), inverse_gensym_map (units_gensyms)),
-      reunitified : subst (reunitification_eqs, apply (e%_op, unitless_args)),
-      rezeroified : subst (makelist (x = 0, x, listarray (qtys_gensyms)), reunitified),
+      reunitified : sublis (reunitification_eqs, apply (e%_op, unitless_args)),
+      rezeroified : sublis (makelist (x = 0, x, listarray (qtys_gensyms)), reunitified),
       killcontext (context_name),
       rezeroified));
 
diff --git a/share/ezunits/rtest_ezunits_mroz_examples.mac b/share/ezunits/rtest_ezunits_mroz_examples.mac
index 894958284..f624b0a98 100644
--- a/share/ezunits/rtest_ezunits_mroz_examples.mac
+++ b/share/ezunits/rtest_ezunits_mroz_examples.mac
@@ -50,3 +50,23 @@ true;
  e6h: approximately_equal (e6g, 0.0031 ` (1/nF), 0.00005));
 true;
 
+/* maxima-discuss 2026-06-01, "Solving Equation with Ezunits Problem" */
+
+(R_1: 1 `kOhm,
+ R_2: 100 `Ohm,
+ V_1: 10 `V,
+ I: 3/2 `mA,
+ expr: V_1 = (R_1 + R_2) * I + V_2);
+10 ` V=V_2+(3/2 ` mA)*(100 ` Ohm+1 ` kOhm);
+
+foo1: solve(expr, V_2)[1];
+V_2=10 ` V+-(3/2) ` kOhm*mA+-150 ` Ohm*mA;
+
+rhs(foo1) ``V;
+167/20 ` V;
+
+foo2: dimensionally(solve(expr, V_2))[1];
+V_2 = -((300 ` Ohm*mA+3 ` kOhm*mA+(-20) ` V)/2);
+
+rhs(foo2) ``V;
+167/20 ` V;

-----------------------------------------------------------------------

Summary of changes:
 share/ezunits/ezunits_functions.mac           |  4 ++--
 share/ezunits/rtest_ezunits_mroz_examples.mac | 20 ++++++++++++++++++++
 2 files changed, 22 insertions(+), 2 deletions(-)


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