function $op(lax::Union{Cint,Int}, z::Union{Cdouble,Float64,Int};

        function $op(lmax::Union{Cint,Int}, z::Union{Cdouble,Float64,Int};

            p = Array{Cdouble}(undef, (lax + 1) * (lax + 2) ÷ 2)

            p = Array{Cdouble}(undef, (lmax + 1) * (lmax + 2) ÷ 2)

                  (Ptr{Cdouble}, Cint, Cdouble, Ref{Cint}), p, lax, z,

                  (Ptr{Cdouble}, Cint, Cdouble, Ref{Cint}), p, lmax, z,

        function $op_d1(lax::Union{Cint,Int}, z::Union{Cdouble,Float64,Int};

        function $op_d1(lmax::Union{Cint,Int}, z::Union{Cdouble,Float64,Int};

            p = Array{Cdouble}(undef, (lax + 1) * (lax + 2) ÷ 2)
            dp = Array{Cdouble}(undef, (lax + 1) * (lax + 2) ÷ 2)

            p = Array{Cdouble}(undef, (lmax + 1) * (lmax + 2) ÷ 2)
            dp = Array{Cdouble}(undef, (lmax + 1) * (lmax + 2) ÷ 2)

                  lax, z, cmayberef(Cint, exitstatus))

                  lmax, z, cmayberef(Cint, exitstatus))

export PlmIndex
function PlmIndex(l::Union{Cint,Int}, m::Union{Cint,Int})::Int
    0 ≤ m ≤ l ||
        error("m must be greater than or equal to zero and less than or equal to l: m=$m, l=$l")
    index = ccall((:PlmIndex, libSHTOOLS), Cint, (Cint, Cint), l, m)
    return index

end

index = PlmIndex(4, 3)
@test index == 14