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Performance improvements #24

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Performance improvements #24

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17 changes: 11 additions & 6 deletions src/PolynomialRoots.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -607,15 +607,20 @@ function roots(poly::AbstractVector{<:Number}, roots::AbstractVector{<:Number};
epsilon, degree, polish)
end

# Returns a view into the polynomial that excludes any trailing zero
# coefficients.
#
# Errors if the coefficients are all zero.
function normalized_poly_coefs(poly::AbstractVector{<:Number})
l = findlast(!iszero, poly)
isnothing(l) && error("zero polynomial")
@view poly[begin:l]
end

function roots(poly::AbstractVector{N}; epsilon::AbstractFloat=NaN,
polish::Bool=false) where {N<:Number}
# Before starting, truncate the polynomial if it has zeros in the trailing elements
last_nz = findlast(!iszero, poly)
if lastindex(poly) == last_nz
_poly = poly
else
_poly = poly[1:last_nz]
end
_poly = normalized_poly_coefs(poly)
degree = length(_poly) - 1
roots!(zeros(Complex{real(float(N))}, degree), float.(complex(_poly)),
epsilon, degree, polish)
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