Problem with ImplicitEquation involving the incomplete gamma function

Hi everyone,

I am new to Julia and trying to plot an implicit function involving incomplete gamma function Q(x, a) with the code below (gamma_inc returns a two-element tuple and I only need the second element, so the index [2] is used)

using SpecialFunctions
using Plots, ImplicitEquations 

f(phi, z) = z*gamma_inc((floor(1/phi) - 1), z)[2]
plot(f ⩵ 1; xlims = (0,0.26), ylims = (0, 16))

however it keeps giving the following error messages:

MethodError: no method matching _gamma_inc(::ImplicitEquations.OInterval, ::ImplicitEquations.OInterval, ::Int64)
Closest candidates are:
  _gamma_inc(::Float64, ::Float64, ::Integer) at C:\Users\.julia\packages\SpecialFunctions\FhmL1\src\gamma_inc.jl:860
  _gamma_inc(::BigFloat, ::BigFloat, ::Integer) at C:\Users\.julia\packages\SpecialFunctions\FhmL1\src\gamma_inc.jl:950
  _gamma_inc(::Float32, ::Float32, ::Integer) at C:\Users\.julia\packages\SpecialFunctions\FhmL1\src\gamma_inc.jl:956

Does this imply that the gamma_inc function (from the SpecialFunctions package) doesn’t work with ImplicitEquations? Thanks.

Try GitHub - saschatimme/ImplicitPlots.jl: Julia package for the plotting of plane curves and surfaces which doesn’t use interval arithmetic. It is faster too. There is also IntervalConstraintProgramming.jl

Thank you! I’ll try them.