change name, add docs

Author: vyudu

docs/src/tutorials/initialization.md

@@ -536,3 +536,13 @@ sol[α * x - β * x * y]
 ```@example init
 plot(sol)
 ```
+
+## Summary of Initialization API
+```@docs; canonical=false
+Initial
+isinitial
+generate_initializesystem
+initialization_equations
+guesses
+defaults
+```

src/ModelingToolkit.jl

@@ -286,7 +286,7 @@ export toexpr, get_variables
 export simplify, substitute
 export build_function
 export modelingtoolkitize
-export generate_initializesystem, Initial, isInitial
+export generate_initializesystem, Initial, isinitial
 
 export alg_equations, diff_equations, has_alg_equations, has_diff_equations
 export get_alg_eqs, get_diff_eqs, has_alg_eqs, has_diff_eqs

src/systems/abstractsystem.jl

@@ -720,7 +720,7 @@ end
 """
 Returns true if the parameter `p` is of the form `Initial(x)`.
 """
-function isInitial(p)
+function isinitial(p)
     p = unwrap(p)
     if iscall(p)
         operation(p) isa Initial && return true

test/variable_utils.jl

@@ -146,15 +146,15 @@ end
     end
 end
 
-@testset "isInitial" begin
+@testset "isinitial" begin
     t = ModelingToolkit.t_nounits
     @variables x(t) z(t)[1:5]
     @parameters a b c[1:4]
-    @test isInitial(Initial(z))
-    @test isInitial(Initial(x))
-    @test isInitial(Initial(a))
-    @test isInitial(Initial(z[1]))
-    @test isInitial(Initial(c[4]))
-    @test !isInitial(c)
-    @test !isInitial(x)
+    @test isinitial(Initial(z))
+    @test isinitial(Initial(x))
+    @test isinitial(Initial(a))
+    @test isinitial(Initial(z[1]))
+    @test isinitial(Initial(c[4]))
+    @test !isinitial(c)
+    @test !isinitial(x)
 end