Read these instruction first.

PORTA http://typo.zib.de/opt-long_projects/Software/Porta/

Maxima http://maxima.sourceforge.net/

1/5(1,2,3) singularity

n₀ < n₂ < n₁ < n₄ < n₃
0 < 1 < 2 < 3 < 4
θ _i = n _i - n _i-2
θ ₀ = −4, θ ₁ = −1, θ ₂ = 1, θ ₃ = 2, θ ₄ = 2,

523.ieq 523.wxm 523.poi 523.poi.ieq.poi.ieq

1/7(1,2,5) singularity

n₀ < n₂ < n₁ < n₄ < n₃ < n₆ < n₅
0 < 1 < 2 < 3 < 4 < 5 < 6
θ _i = n _i - n _i-2
θ ₀ = −6, θ ₁ = −3, θ ₂ = 1, θ ₃ = 2, θ ₄ = 2, θ ₅ = 2, θ ₆ = 2,

725.ieq 725.wxm 725.poi 725.poi.ieq.poi.ieq

different choice of theta

n₀ < n₂ < n₁ < n₄ < n₃ < n₆ < n₅
0 < 1 < 3 < 4 < 5 < 7 < 8
θ _i = n _i - n _i-2
θ ₀ = −8, θ ₁ = −4, θ ₂ = 1, θ ₃ = 2, θ ₄ = 3, θ ₅ = 3, θ ₆ = 3,

725bis.ieq 725bis.wxm 725bis.poi 725bis.poi.ieq.poi.ieq

1/7(1,3,4) singularity

n₀ < n₃ < n₂ < n₁ < n₆ < n₅ < n₄
0 < 1 < 2 < 3 < 4 < 5 < 6
θ _i = n _i - n _i-3
θ ₀ = −6, θ ₁ = −2, θ ₂ = −2, θ ₃ = 1, θ ₄ = 3, θ ₅ = 3, θ ₆ = 3,

734.ieq 734.wxm 734.poi 734.poi.ieq.poi.ieq

different choice of theta

n₀ < n₃ < n₂ < n₁ < n₆ < n₅ < n₄
0 < 1 < 2 < 4 < 5 < 6 < 9
θ _i = n _i - n _i-3
θ ₀ = −9, θ ₁ = −2, θ ₂ = −3, θ ₃ = 1, θ ₄ = 5, θ ₅ = 4, θ ₆ = 4,

734bis.ieq 734bis.wxm 734bis.poi 734bis.poi.ieq.poi.ieq