Merge pull request #165 from SciML/bgc/input_fix

Input changed to SampledData

docs/pages.jl

@@ -5,7 +5,7 @@ pages = [
         "Custom Components" => "tutorials/custom_component.md",
         "Thermal Conduction Model" => "tutorials/thermal_model.md",
         "DC Motor with Speed Controller" => "tutorials/dc_motor_pi.md",
-        "Input Component" => "tutorials/input_component.md",
+        "SampledData Component" => "tutorials/input_component.md",
     ],
     "About Acausal Connections" => "connectors/connections.md",
     "API" => [

docs/src/tutorials/input_component.md

@@ -1,16 +1,16 @@
 # Running Models with Discrete Data
 
-There are 2 ways to include data as part of a model.
+There are 3 ways to include data as part of a model.
 
  1. using `ModelingToolkitStandardLibrary.Blocks.TimeVaryingFunction`
- 2. using a custom component with external data or sensor
- 3. using `ModelingToolkitStandardLibrary.Blocks.Input`
+ 2. using a custom component with external data
+ 3. using `ModelingToolkitStandardLibrary.Blocks.SampledData`
 
 This tutorial demonstrate each case and explain the pros and cons of each.
 
-## TimeVaryingFunction Component
+## `TimeVaryingFunction` Component
 
-This component is easy to use and is performative.  However the data is locked to the `ODESystem` and can only be changed by building a new `ODESystem`.  Therefore, running a batch of data would not be efficient.  Below is an example of how to use the `TimeVaryingFunction` with `DataInterpolations` to build the function from discrete data.
+The `ModelingToolkitStandardLibrary.Blocks.TimeVaryingFunction` component is easy to use and is performative.  However the data is locked to the `ODESystem` and can only be changed by building a new `ODESystem`.  Therefore, running a batch of data would not be efficient.  Below is an example of how to use the `TimeVaryingFunction` with `DataInterpolations` to build the function from sampled discrete data.
 
 ```julia
 using ModelingToolkit
@@ -47,11 +47,11 @@ prob = ODEProblem(sys, [], (0, time[end]))
 sol = solve(prob, ImplicitEuler())
 ```
 
-If we want to run a new data set, this requires building a new `LinearInterpolation` and `ODESystem` followed by running `structural_simplify`, all of which takes time.  Therefore, to run serveral pieces of data it's better to re-use an `ODESystem`.  The next couple methods will demonstrate this.
+If we want to run a new data set, this requires building a new `LinearInterpolation` and `ODESystem` followed by running `structural_simplify`, all of which takes time.  Therefore, to run serveral pieces of data it's better to re-use an `ODESystem`.  The next couple methods will demonstrate how to do this.
 
 ## Custom Component with External Data
 
-The below code shows how to include data using a `Ref` and registered `input` function.  This example uses a very basic function which requires non-adaptive solving and sampled data.  As can be seen, the data can easily be set and changed before solving.
+The below code shows how to include data using a `Ref` and registered `get_sampled_data` function.  This example uses a very basic function which requires non-adaptive solving and sampled data.  As can be seen, the data can easily be set and changed before solving.
 
 ```julia
 const rdata = Ref{Vector{Float64}}()
@@ -60,20 +60,20 @@ const rdata = Ref{Vector{Float64}}()
 data1 = sin.(2 * pi * time * 100)
 data2 = cos.(2 * pi * time * 50)
 
-function input(t)
+function get_sampled_data(t)
     i = floor(Int, t / dt) + 1
     x = rdata[][i]
 
     return x
 end
 
-Symbolics.@register_symbolic input(t)
+Symbolics.@register_symbolic get_sampled_data(t)
 
 function System(; name)
     vars = @variables f(t)=0 x(t)=0 dx(t)=0 ddx(t)=0
     pars = @parameters m=10 k=1000 d=1
 
-    eqs = [f ~ input(t)
+    eqs = [f ~ get_sampled_data(t)
            ddx * 10 ~ k * x + d * dx + f
            D(x) ~ dx
            D(dx) ~ ddx]
@@ -94,20 +94,22 @@ sol2 = solve(prob, ImplicitEuler(); dt, adaptive = false)
 ddx2 = sol2[sys.ddx]
 ```
 
-The drawback of this method is that the solution observables can be linked to the data `Ref`, which means that if the data changes then the observables are no longer valid.  In this case `ddx` is an observable that is derived directly from the data.  Therefore, `sol1[sys.ddx]` is no longer correct after the data is changed for `sol2`.  Additional code could be added to resolve this issue, for example by using a `Ref{Dict}` that could link a parameter of the model to the data source.  This would also be necessary for parallel processing.
+The drawback of this method is that the solution observables can be linked to the data `Ref`, which means that if the data changes then the observables are no longer valid.  In this case `ddx` is an observable that is derived directly from the data.  Therefore, `sol1[sys.ddx]` is no longer correct after the data is changed for `sol2`.
 
 ```julia
 # the following test will fail
 @test all(ddx1 .== sol1[sys.ddx]) #returns false
 ```
 
-## Input Component
+Additional code could be added to resolve this issue, for example by using a `Ref{Dict}` that could link a parameter of the model to the data source.  This would also be necessary for parallel processing.
 
-To resolve the issues presented above, the `Input` component can be used which allows for a resusable `ODESystem` and self contained data which ensures a solution which remains valid for it's lifetime.  Now it's possible to also parallize the solving.
+## `SampledData` Component
+
+To resolve the issues presented above, the `ModelingToolkitStandardLibrary.Blocks.SampledData` component can be used which allows for a resusable `ODESystem` and self contained data which ensures a solution which remains valid for it's lifetime.  Now it's possible to also parallize the call to `solve()`.
 
 ```julia
 function System(; name)
-    src = Input(Float64)
+    src = SampledData(Float64)
 
     vars = @variables f(t)=0 x(t)=0 dx(t)=0 ddx(t)=0
     pars = @parameters m=10 k=1000 d=1
@@ -144,4 +146,4 @@ sol2 = Ref{ODESolution}()
 end
 ```
 
-Note, in the above example, we can build the system with an empty `Input` component, only setting the expected data type: `@named src = Input(Float64)`.  It's also possible to initialize the component with real data: `@named src = Input(data, dt)`.  Additionally note that before running an `ODEProblem` using the `Input` component that the parameter vector should be a uniform type so that Julia is not slowed down by type instability.  Because the `Input` component contains the `buffer` parameter of type `Parameter`, we must generate the problem using `tofloat=false`.  This will initially give a parameter vector of type `Vector{Any}` with a mix of numbers and `Parameter` type.  We can convert the vector to all `Parameter` type by running `p = Parameter.(p)`.  This will wrap all the single values in a `Parameter` type which will be mathmatically equivalent to a `Number`.
+Note, in the above example, we can build the system with an empty `SampledData` component, only setting the expected data type: `@named src = SampledData(Float64)`.  It's also possible to initialize the component with real sampled data: `@named src = SampledData(data, dt)`.  Additionally note that before running an `ODEProblem` using the `SampledData` component, one must be careful about the parameter vector Type.  The `SampledData` component contains a `buffer` parameter of type `Parameter`, therefore we must generate the problem using `tofloat=false`.  This will initially give a parameter vector of type `Vector{Any}` with a mix of numbers and `Parameter` type.  We can convert the vector to a uniform `Parameter` type by running `p = Parameter.(p)`.  This will wrap all the single values in a `Parameter` which will be mathmatically equivalent to a `Number`.

src/Blocks/Blocks.jl

@@ -18,7 +18,7 @@ export Log, Log10
 include("math.jl")
 
 export Constant, TimeVaryingFunction, Sine, Cosine, ContinuousClock, Ramp, Step, ExpSine,
-       Square, Triangular, Parameter, Input
+       Square, Triangular, Parameter, SampledData
 include("sources.jl")
 
 export Limiter, DeadZone, SlewRateLimiter

src/Blocks/sources.jl

@@ -488,18 +488,14 @@ function Parameter(x::T; tofloat = true) where {T <: Real}
 end
 Parameter(x::Vector{T}, dt::T) where {T <: Real} = Parameter(x, dt, length(x))
 
-function input(t, memory::Parameter{T}) where {T}
+function get_sampled_data(t, memory::Parameter{T}) where {T}
     if t < 0
         t = zero(t)
     end
 
     if isempty(memory.data)
-        if T isa Float16
-            return NaN16
-        elseif T isa Float32
-            return NaN32
-        elseif T isa Float64
-            return NaN64
+        if T <: AbstractFloat
+            return T(NaN)
         else
             return zero(T)
         end
@@ -528,27 +524,27 @@ end
 get_sample_time(memory::Parameter) = memory.ref
 Symbolics.@register_symbolic get_sample_time(memory)
 
-Symbolics.@register_symbolic input(t, memory)
+Symbolics.@register_symbolic get_sampled_data(t, memory)
 
 function first_order_backwards_difference(t, memory)
     Δt = get_sample_time(memory)
-    x1 = input(t, memory)
-    x0 = input(t - Δt, memory)
+    x1 = get_sampled_data(t, memory)
+    x0 = get_sampled_data(t - Δt, memory)
 
     return (x1 - x0) / Δt
 end
 
-function Symbolics.derivative(::typeof(input), args::NTuple{2, Any}, ::Val{1})
+function Symbolics.derivative(::typeof(get_sampled_data), args::NTuple{2, Any}, ::Val{1})
     first_order_backwards_difference(args[1], args[2])
 end
 
-Input(T::Type; name) = Input(T[], zero(T); name)
-function Input(data::Vector{T}, dt::T; name) where {T <: Real}
-    Input(; name, buffer = Parameter(data, dt))
+SampledData(T::Type; name) = SampledData(T[], zero(T); name)
+function SampledData(data::Vector{T}, dt::T; name) where {T <: Real}
+    SampledData(; name, buffer = Parameter(data, dt))
 end
 
 """
-    Input(; name, buffer)
+    SampledData(; name, buffer)
 
 data input component.  
 
@@ -558,13 +554,14 @@ data input component.
 # Connectors:
   - `output`
 """
-@component function Input(; name, buffer)
+@component function SampledData(; name, buffer)
     pars = @parameters begin buffer = buffer end
     vars = []
     systems = @named begin output = RealOutput() end
     eqs = [
-        output.u ~ input(t, buffer),
+        output.u ~ get_sampled_data(t, buffer),
     ]
     return ODESystem(eqs, t, vars, pars; name, systems,
-                     defaults = [output.u => input(0.0, buffer)]) #TODO: get initial value from buffer
+                     defaults = [output.u => get_sampled_data(0.0, buffer)])
 end
+@deprecate Input SampledData

src/Hydraulic/IsothermalCompressible/IsothermalCompressible.jl

@@ -16,7 +16,10 @@ D = Differential(t)
 export HydraulicPort, HydraulicFluid
 include("utils.jl")
 
-export Source, InputSource, Cap, Tube, FixedVolume, DynamicVolume
+export Cap, Tube, FixedVolume, DynamicVolume
 include("components.jl")
 
+export MassFlow, Pressure, FixedPressure
+include("sources.jl")
+
 end