Suggested changes made

Author: ParamThakkar123

lib/OrdinaryDiffEqFIRK/src/OrdinaryDiffEqFIRK.jl

@@ -13,7 +13,7 @@ import OrdinaryDiffEq: alg_order, calculate_residuals!,
                        NLStatus, qmax_default, alg_adaptive_order, DEFAULT_PRECS,
                        UJacobianWrapper, build_J_W, build_jac_config, UDerivativeWrapper,
                        Convergence, calc_J!, dolinsolve, FastConvergence, calc_J,
-                       mul!
+                       mul!, PredictiveController
 using MuladdMacro, DiffEqBase, RecursiveArrayTools
 using SciMLOperators: AbstractSciMLOperator
 using LinearAlgebra: I, UniformScaling

lib/OrdinaryDiffEqFIRK/src/alg_utils.jl

@@ -4,6 +4,10 @@ alg_order(alg::RadauIIA3) = 3
 alg_order(alg::RadauIIA5) = 5
 alg_order(alg::RadauIIA7) = 7
 
+isfirk(alg::RadauIIA3) = true
+isfirk(alg::RadauIIA5) = true
+isfirk(alg::RadauIIA7) = true
+
 alg_adaptive_order(alg::RadauIIA3) = 1
 alg_adaptive_order(alg::RadauIIA5) = 3
 alg_adaptive_order(alg::RadauIIA7) = 5

lib/OrdinaryDiffEqFIRK/src/controllers.jl

@@ -1,6 +1,3 @@
-struct PredictiveController <: AbstractController
-end
-
 @inline function stepsize_controller!(integrator, controller::PredictiveController, alg)
     @unpack qmin, qmax, gamma = integrator.opts
     EEst = DiffEqBase.value(integrator.EEst)
@@ -11,7 +8,7 @@ end
         if fac_default_gamma(alg)
             fac = gamma
         else
-            if alg isa Union{RadauIIA3, RadauIIA5, RadauIIA7}
+            if isfirk(alg::Union{RadauIIA3, RadauIIA5, RadauIIA7})
                 @unpack iter = integrator.cache
                 @unpack maxiters = alg
             else

src/alg_utils.jl

@@ -50,6 +50,8 @@ isfsal(alg::PSRK3p5q4) = false
 isfsal(alg::PSRK3p6q5) = false
 isfsal(alg::PSRK4p7q6) = false
 
+isfirk(alg) = false
+
 get_current_isfsal(alg, cache) = isfsal(alg)
 
 # evaluates f(t[i])

src/integrators/controllers.jl

@@ -1,9 +1,6 @@
 abstract type AbstractController end
 using OrdinaryDiffEq
 
-struct PredictiveController <: AbstractController
-end
-
 @inline function stepsize_controller!(integrator, alg)
     stepsize_controller!(integrator, integrator.opts.controller, alg)
 end
@@ -397,6 +394,9 @@ end
 ```
 """
 
+struct PredictiveController <: AbstractController
+end
+
 # Dummy controller without any method implementations.
 # This is used to transfer the special controllers associated to certain
 # algorithms to the new controller infrastructure with