Minor fixes - review carefully

.gitignore

@@ -4,3 +4,4 @@
 deps/deps.jl
 *.mem
 *.h5
+.vscode/settings.json

src/LinearOps.jl

@@ -3,23 +3,32 @@ import FFTW
 import Luna: Modes, Grid, PhysData
 import Luna.PhysData: wlfreq
 
+# limit α so that we do not get overflow in exp(α*dz)
+function αlim!(α)
+    # magic number: this is 1300 dB/m it could probably be bigger
+    α[α .> 300] .= 300
+end
+
 function make_const_linop(grid::Grid.RealGrid, βfun, αfun, frame_vel)
     β = similar(grid.ω)
     βfun(β, grid.ω, 0)
-    α = αfun(grid.ω, 0)
+    α = zeros(length(grid.ω))
+    α[2:end] .= αfun(grid.ω[2:end], 0)
+    αlim!(α)
     β1 = 1/frame_vel(0)
     linop = @. -im*(β-β1*grid.ω) - α/2
-    linop[1] = 1
+    linop[1] = 0
     return linop
 end
 
 function make_const_linop(grid::Grid.EnvGrid, βfun, αfun, frame_vel, β0ref)
     β = similar(grid.ω)
     βfun(β, grid.ω, 0)
     α = αfun(grid.ω, 0)
+    αlim!(α)
     β1 = 1/frame_vel(0)
     linop = -im.*(β .- β1.*(grid.ω .- grid.ω0) .- β0ref) .- α./2
-    linop[.!grid.sidx] .= 1
+    linop[.!grid.sidx] .= 0
     return linop
 end
 
@@ -62,7 +71,9 @@ function make_const_linop(grid::Grid.RealGrid, modes, λ0; ref_mode=1)
         βconst = zero(grid.ω)
         βconst[2:end] = Modes.β.(modes[i], grid.ω[2:end])
         βconst[1] = 1
-        α = Modes.α.(modes[i], grid.ω)
+        α = zeros(length(grid.ω))
+        α[2:end] .= Modes.α.(modes[i], grid.ω[2:end])
+        αlim!(α)
         linops[:,i] = im.*(-βconst .+ grid.ω./vel) .- α./2
     end
     linops
@@ -82,6 +93,7 @@ function make_const_linop(grid::Grid.EnvGrid, modes, λ0; ref_mode=1, thg=false)
         βconst[grid.sidx] = Modes.β.(modes[i], grid.ω[grid.sidx])
         βconst[.!grid.sidx] .= 1
         α = Modes.α.(modes[i], grid.ω)
+        αlim!(α)
         linops[:,i] = -im.*(βconst .- (grid.ω .- grid.ω0)./vel .- βref) .- α./2
     end
     linops