Currently working on refactor, much work to do

julia/src/inner_loop/propagator.jl

@@ -18,18 +18,15 @@ A convenience function for using spacecraft. Note that this function outputs a s
 function prop_one(ΔV_unit::Vector{<:Real},
                   state::Vector{<:Real},
                   craft::Sc,
-                  μ::Float64,
-                  time::Float64)
+                  time::Float64,
+                  primary::Body=Sun)
 
   for direction in ΔV_unit
-    if abs(direction) > 1.0
-      println(direction)
-      error("ΔV is impossibly high")
-    end
+    abs(direction) <= 1.0 || throw(PropOne_Error(ΔV_unit))
   end
   ΔV = max_ΔV(craft.duty_cycle, craft.num_thrusters, craft.max_thrust, time, 0., state[7]) * ΔV_unit
-  halfway = laguerre_conway(state, μ, time/2) + [zeros(3); ΔV]
-  final = laguerre_conway(halfway, μ, time/2)
+  halfway = laguerre_conway(state, time/2, primary) + [zeros(3); ΔV]
+  final = laguerre_conway(halfway, time/2, primary)
   return [final; state[7] - craft.mass_flow_rate*norm(ΔV_unit)*time]
 
 end
@@ -40,10 +37,10 @@ The propagator function
 function prop(ΔVs::Matrix{T},
               state::Vector{Float64},
               craft::Sc,
-              μ::Float64,
-              time::Float64) where T <: Real
+              time::Float64,
+              primary::Body=Sun) where T <: Real
 
-  if size(ΔVs)[2] != 3 throw(ErrorException("ΔV input is wrong size")) end
+  size(ΔVs)[2] == 3 || throw(ΔVsize_Error())
   n = size(ΔVs)[1]
 
   x_states = Vector{T}()
@@ -63,7 +60,7 @@ function prop(ΔVs::Matrix{T},
   push!(masses, state[7])
 
   for i in 1:n
-    state = prop_one(ΔVs[i,:], state, craft, μ, time/n)
+    state = prop_one(ΔVs[i,:], state, craft, time/n, primary)
     push!(x_states, state[1])
     push!(y_states, state[2])
     push!(z_states, state[3])
@@ -71,12 +68,14 @@ function prop(ΔVs::Matrix{T},
     push!(dy_states, state[5])
     push!(dz_states, state[6])
     push!(masses, state[7])
-    if state[7] < craft.dry_mass
-      println(state[7])
-      error("Mass is too low")
-    end
+    state[7] >= craft.dry_mass || throw(Mass_Error(state[7]))
   end
 
   return [x_states, y_states, z_states, dx_states, dy_states, dz_states, masses], state
 
 end
+
+"""
+Convenience function for propagating a state with no thrust
+"""
+prop(x::Vector{Float64}, t::Float64, p::Body=Sun) = prop(zeros(1000,3), x, no_thrust, t, p)[1]