Merge pull request #1681 from JuliaSymbolics/as/fix-bugs

fix: respect new dependent variable semantics in a few places

Author: AayushSabharwal

Project.toml

@@ -114,7 +114,7 @@ SymPy = "2.2"
 SymPyPythonCall = "0.5"
 SymbolicIndexingInterface = "0.3.14"
 SymbolicLimits = "0.2.2"
-SymbolicUtils = "4.3"
+SymbolicUtils = "4.4"
 TermInterface = "2"
 julia = "1.10"
 

src/diff.jl

@@ -256,6 +256,24 @@ function substitute_in_deriv(ex, rules; kw...)
     substitute(ex, rules; kw..., filterer = symdiff_substitute_filter)
 end
 
+function deriv_and_depvar_substitute_filter(ex::SymbolicT)
+    SymbolicUtils.default_substitute_filter(ex) || @match ex begin
+        BSImpl.Term(; f) && if f isa Differential end => true
+        BSImpl.Term(; f) && if f isa SymbolicT end => true
+        _ => false
+    end
+end
+
+"""
+    $(TYPEDSIGNATURES)
+
+Identical to `substitute` except it also substitutes inside `Differential` operator
+applications and dependent variables.
+"""
+function substitute_in_deriv_and_depvar(ex, rules; kw...)
+    substitute(ex, rules; kw..., filterer = deriv_and_depvar_substitute_filter)
+end
+
 function chain_diff(D::Differential, arg::BasicSymbolic{VartypeT}, inner_args::SymbolicUtils.ROArgsT{VartypeT}; kw...)
     any(isequal(D.x), inner_args) && return D(arg)
 
@@ -358,12 +376,12 @@ function executediff(D::Differential, arg::BasicSymbolic{VartypeT}; simplify=fal
                 summed_args = SymbolicUtils.ArgsT{VartypeT}()
                 inner_function = arguments(arg)[1]
                 if iscall(a) || isequal(a, D.x)
-                    t1 = substitute_in_deriv(inner_function, Dict(domainvars => a))
+                    t1 = substitute_in_deriv_and_depvar(inner_function, Dict(domainvars => a))
                     t2 = executediff(D, a; simplify, throw_no_derivative)
                     push!(summed_args, -t1*t2)
                 end
                 if iscall(b) || isequal(b, D.x)
-                    t1 = substitute_in_deriv(inner_function, Dict(domainvars => b))
+                    t1 = substitute_in_deriv_and_depvar(inner_function, Dict(domainvars => b))
                     t2 = executediff(D, b; simplify, throw_no_derivative)
                     push!(summed_args, t1*t2)
                 end

test/runtests.jl

@@ -61,7 +61,6 @@ if GROUP == "All" || GROUP == "Core"
         @safetestset "LogExpFunctions Test" begin include("logexpfunctions.jl") end
         @safetestset "Registration without using Test" begin include("registration_without_using.jl") end
         @safetestset "Show Test" begin include("show.jl") end
-        @safetestset "Utility Function Test" begin include("utils.jl") end
         @safetestset "RootFinding solver" begin include("solver.jl") end
         @safetestset "Function inverses test" begin include("inverse.jl") end
         @safetestset "Taylor Series Test" begin include("taylor.jl") end

test/utils.jl

@@ -62,7 +62,7 @@ end
 end
 
 @testset "Issue#1342 substitute working on called symbolics" begin
-    @variables p(..) x y
+    @variables p(::Real) x y
     arg = unwrap(substitute(p(x), [p => identity]))
     @test iscall(arg) && operation(arg) == identity && isequal(only(arguments(arg)), x)
     @test unwrap_const(unwrap(substitute(p(x), [p => sqrt, x => 4.0]; fold = Val(true)))) ≈ 2.0