Add 'asinclamp' helper function

src/crs/projected/albers.jl

@@ -98,7 +98,7 @@ function backward(::Type{<:Albers{latₒ,lat₁,lat₂,Datum}}, x, y) where {lat
   θ = n ≥ 0 ? atan(x, ρₒ - y) : atan(-x, y - ρₒ)
   ρ′ = sqrt(x^2 + (ρₒ - y)^2)
   α′ = (C - (ρ′^2 * n^2)) / n
-  β′ = asin(α′ / (1 - ((1 - e²) / (2 * e)) * log((1 - e) / (1 + e))))
+  β′ = asinclamp(α′ / (1 - ((1 - e²) / (2 * e)) * log((1 - e) / (1 + e))))
 
   λ = θ / n
   ϕ = auth2geod(β′, e²)

src/crs/projected/orthographic.jl

@@ -160,18 +160,17 @@ Base.convert(::Type{Orthographic{Mode,latₒ}}, coords::CRS{Datum}) where {Mode,
 # -----------------
 
 function sphericalinv(x, y, λₒ, ϕₒ)
-  fix(x) = clamp(x, -one(x), one(x))
   ρ = hypot(x, y)
   if ρ < atol(x)
     λₒ, ϕₒ
   else
-    c = asin(fix(ρ))
+    c = asinclamp(ρ)
     sinc = sin(c)
     cosc = cos(c)
     sinϕₒ = sin(ϕₒ)
     cosϕₒ = cos(ϕₒ)
     λ = atan(x * sinc, ρ * cosϕₒ * cosc - y * sinϕₒ * sinc)
-    ϕ = asin(fix(cosc * sinϕₒ + (y * sinc * cosϕₒ / ρ)))
+    ϕ = asinclamp(cosc * sinϕₒ + (y * sinc * cosϕₒ / ρ))
     λ, ϕ
   end
 end

src/utils.jl

@@ -64,6 +64,13 @@ function atanpos(y, x)
   ifelse(α ≥ zero(α), α, α + oftype(α, 2π))
 end
 
+"""
+    asinclamp(x)
+
+Adjust `x` to the range `[-1,1]` to handle floating-point errors.
+"""
+asinclamp(x) = asin(clamp(x, -one(x), one(x)))
+
 """
     checklat(lat)