diff --git a/Project.toml b/Project.toml
index fee1602..b76b23a 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "NonlinearNormalForm"
 uuid = "05e19671-dec8-4f15-984f-54eaa6ca64be"
 authors = ["Matt Signorelli"]
-version = "0.3.0"
+version = "0.3.1"
 
 [deps]
 DelimitedFiles = "8bb1440f-4735-579b-a4ab-409b98df4dab"
diff --git a/src/matrix.jl b/src/matrix.jl
index c5ec99d..9038ab9 100644
--- a/src/matrix.jl
+++ b/src/matrix.jl
@@ -5,6 +5,8 @@ Given a matrix `mat` with an even number of rows/cols, calculates the eigenvecto
 and eigenvalues. For stable eigenmodes (complex conjugate eigenvector/eigenvalue pairs), 
 the eigenvectors are normalized so that `vⱼ'*S*vⱼ = +im` for odd `j`, and `-im` for even `j`.
 
+If `error_unstable` is `true` (default), then an error will be thrown if any mode is unstable.
+
 If `sort` is true, then each eigenvector/eigenvalue pair will be sorted according to the mode 
 it best identifies with. A warning will be printed if the mode sorting fails. Mode sorting 
 will automatically fail if more than 1 mode is unstable. Default is true.
@@ -18,10 +20,10 @@ phase factor is harmless/useless to include in a highly-coupled matrix.
 
 For complex matrices, Julia's `eigen`, which is called by `mat_eigen`, is type-unstable.
 """
-function mat_eigen(mat; sort=true, phase_modes=true)
+function mat_eigen(mat; sort=true, phase_modes=true, error_unstable=true)
   F = eigen(mat)
   F = make_mutable(F)
-  low_mat_eigen!(F, sort, phase_modes)
+  low_mat_eigen!(F, sort, phase_modes, error_unstable)
   return F
 end
 
@@ -31,10 +33,10 @@ end
 Same as `mat_eigen`, but mutates `mat` for speed. See the documentation for `mat_eigen` 
 for more details.
 """
-function mat_eigen!(mat; sort=true, phase_modes=true)
+function mat_eigen!(mat; sort=true, phase_modes=true, error_unstable=true)
   F = eigen!(mat)
   F = make_mutable(F)
-  low_mat_eigen!(F, sort, phase_modes)
+  low_mat_eigen!(F, sort, phase_modes, error_unstable)
   return F
 end
 
@@ -52,10 +54,14 @@ function make_mutable(F::Eigen{S,T,U,V}) where {S,T,U,V}
   end
 end
 
-function low_mat_eigen!(F, sort, phase_modes)
+function low_mat_eigen!(F, sort, phase_modes, error_unstable)
   # Move unstable modes to the end:
   num_unstable = moveback_unstable!(F)
 
+  if num_unstable > 0 && error_unstable
+    error("At least one orbital eigenmode is linearly unstable!")
+  end
+
   if sort
     # Attempt to locate modes, but do not sort yet!
     # We must first normalize the stable modes before sorting, 
diff --git a/src/set.jl b/src/set.jl
index 4c78f27..f789eac 100644
--- a/src/set.jl
+++ b/src/set.jl
@@ -3,6 +3,7 @@
 
 function setray!(
   r::AbstractArray{<:T}; 
+  scalar::Union{AbstractVector,Nothing}=nothing,
   v::Union{AbstractVector,Nothing}=nothing,
   v_matrix::Union{AbstractMatrix,UniformScaling,Nothing}=nothing,
   v_matrix_offset::Integer=0,
@@ -11,6 +12,15 @@ function setray!(
 
   length(r) <= ndiffs(first(r)) || error("Length of output orbital ray `r` cannot be greater than the number of differentials in the TPSA!")
 
+  if !isnothing(scalar)
+    length(r) <= length(scalar) || error("Length of input vector `scalar` cannot be greater than the length of output vector `r`!")
+    if TI.is_tps_type(eltype(scalar)) isa TI.IsTPSType # TPS input
+      foreach((out_xi, xi)->TI.seti!(out_xi, TI.geti(xi, 0), 0), view(r, 1:length(scalar)), scalar)
+    else
+      foreach((out_xi, xi)->TI.seti!(out_xi, xi, 0), view(r, 1:length(scalar)), scalar)
+    end
+  end
+
   if !isnothing(v)
     length(v) <= length(r) || error("Length of input vector `v` cannot be greater than the length of output vector `r`!")
     foreach((out_xi, xi)->copy!(out_xi, xi), view(r, 1:length(v)), v)