fix: fix linear indexing of StableIndex, add more utility to it

[AayushSabharwal]

No description provided.

[github-actions]

Benchmark Results (Julia vlts)

Time benchmarks

	master	6d5a680...	master / 6d5a680...
arithmetic/addition	0.0752 ± 0.00089 ms	0.0747 ± 0.00095 ms	1.01 ± 0.018
arithmetic/division	27.9 ± 0.63 μs	28.3 ± 0.71 μs	0.989 ± 0.033
arithmetic/multiplication	0.061 ± 0.0019 ms	0.06 ± 0.0016 ms	1.02 ± 0.042
overhead/acrule/a+2	2.73 ± 0.05 μs	2.89 ± 0.06 μs	0.948 ± 0.026
overhead/acrule/a+2+b	0.07 ± 0.01 μs	0.07 ± 0 μs	1 ± 0.14
overhead/acrule/a+b	4.93 ± 0.14 μs	5.16 ± 0.14 μs	0.955 ± 0.037
overhead/acrule/noop:Int	0.05 ± 0.01 μs	0.05 ± 0.01 μs	1 ± 0.28
overhead/acrule/noop:Sym	0.051 ± 0.01 μs	0.06 ± 0.01 μs	0.85 ± 0.22
overhead/get_degrees/large_poly	0.0977 ± 0.0044 s	0.0982 ± 0.0045 s	0.995 ± 0.064
overhead/rule/noop:Int	0.061 ± 0.01 μs	0.07 ± 0.001 μs	0.871 ± 0.14
overhead/rule/noop:Sym	0.06 ± 0.001 μs	0.06 ± 0.01 μs	1 ± 0.17
overhead/rule/noop:Term	0.06 ± 0.01 μs	0.069 ± 0.01 μs	0.87 ± 0.19
overhead/ruleset/noop:Int	30 ± 0 ns	30 ± 0 ns	1 ± 0
overhead/ruleset/noop:Sym	0.31 ± 0.01 μs	0.311 ± 0.01 μs	0.997 ± 0.045
overhead/ruleset/noop:Term	1.2 ± 0.02 μs	1.19 ± 0.029 μs	1.01 ± 0.03
overhead/simplify/noop:Int	30 ± 0 ns	30 ± 0 ns	1 ± 0
overhead/simplify/noop:Sym	30 ± 10 ns	30 ± 10 ns	1 ± 0.47
overhead/simplify/noop:Term	0.0318 ± 0.0009 ms	0.0326 ± 0.00087 ms	0.974 ± 0.038
overhead/simplify/randterm (+, *):serial	0.258 ± 0.0074 s	0.265 ± 0.007 s	0.975 ± 0.038
overhead/simplify/randterm (+, *):thread	0.322 ± 0.15 s	0.428 ± 0.14 s	0.753 ± 0.43
overhead/simplify/randterm (/, *):serial	0.0896 ± 0.0022 ms	0.0892 ± 0.0018 ms	1 ± 0.032
overhead/simplify/randterm (/, *):thread	0.093 ± 0.0019 ms	0.092 ± 0.0019 ms	1.01 ± 0.03
overhead/substitute/a	0.0511 ± 0.0014 ms	0.0506 ± 0.0013 ms	1.01 ± 0.038
overhead/substitute/a,b	0.064 ± 0.0015 ms	0.0638 ± 0.0017 ms	1 ± 0.036
overhead/substitute/a,b,c	0.0582 ± 0.0014 ms	0.0561 ± 0.0013 ms	1.04 ± 0.034
polyform/easy_iszero	23.4 ± 0.5 μs	22.9 ± 0.49 μs	1.02 ± 0.031
polyform/isone	1.06 ± 0.018 ms	1.09 ± 0.028 ms	0.966 ± 0.03
polyform/isone:noop	0.15 ± 0.01 μs	0.15 ± 0.001 μs	1 ± 0.067
polyform/iszero	0.901 ± 0.014 ms	0.92 ± 0.017 ms	0.979 ± 0.023
polyform/iszero:noop	0.15 ± 0.001 μs	0.15 ± 0.001 μs	1 ± 0.0094
polyform/simplify_fractions	1.18 ± 0.017 ms	1.2 ± 0.024 ms	0.987 ± 0.025
time_to_load	1.19 ± 0.0048 s	1.2 ± 0.016 s	0.992 ± 0.014

Memory benchmarks

	master	6d5a680...	master / 6d5a680...
arithmetic/addition	0.438 k allocs: 16 kB	0.438 k allocs: 16 kB	1
arithmetic/division	0.196 k allocs: 6.83 kB	0.196 k allocs: 6.83 kB	1
arithmetic/multiplication	0.357 k allocs: 11.7 kB	0.357 k allocs: 11.7 kB	1
overhead/acrule/a+2	0.036 k allocs: 1.27 kB	0.036 k allocs: 1.27 kB	1
overhead/acrule/a+2+b	0 allocs: 0 B	0 allocs: 0 B
overhead/acrule/a+b	0.051 k allocs: 1.84 kB	0.051 k allocs: 1.84 kB	1
overhead/acrule/noop:Int	0 allocs: 0 B	0 allocs: 0 B
overhead/acrule/noop:Sym	0 allocs: 0 B	0 allocs: 0 B
overhead/get_degrees/large_poly	0.601 M allocs: 18.9 MB	0.601 M allocs: 18.9 MB	1
overhead/rule/noop:Int	2 allocs: 0.0625 kB	2 allocs: 0.0625 kB	1
overhead/rule/noop:Sym	2 allocs: 0.0625 kB	2 allocs: 0.0625 kB	1
overhead/rule/noop:Term	2 allocs: 0.0625 kB	2 allocs: 0.0625 kB	1
overhead/ruleset/noop:Int	0 allocs: 0 B	0 allocs: 0 B
overhead/ruleset/noop:Sym	3 allocs: 0.109 kB	3 allocs: 0.109 kB	1
overhead/ruleset/noop:Term	12 allocs: 0.391 kB	12 allocs: 0.391 kB	1
overhead/simplify/noop:Int	0 allocs: 0 B	0 allocs: 0 B
overhead/simplify/noop:Sym	0 allocs: 0 B	0 allocs: 0 B
overhead/simplify/noop:Term	0.372 k allocs: 14.2 kB	0.372 k allocs: 14.2 kB	1
overhead/simplify/randterm (+, *):serial	2.86 M allocs: 0.105 GB	2.85 M allocs: 0.105 GB	1
overhead/simplify/randterm (+, *):thread	2.86 M allocs: 0.261 GB	2.86 M allocs: 0.261 GB	1
overhead/simplify/randterm (/, *):serial	0.806 k allocs: 29.8 kB	0.806 k allocs: 29.8 kB	1
overhead/simplify/randterm (/, *):thread	0.831 k allocs: 30.5 kB	0.831 k allocs: 30.5 kB	1
overhead/substitute/a	0.308 k allocs: 11 kB	0.308 k allocs: 11 kB	1
overhead/substitute/a,b	0.394 k allocs: 13.9 kB	0.394 k allocs: 13.9 kB	1
overhead/substitute/a,b,c	0.355 k allocs: 12.1 kB	0.355 k allocs: 12.1 kB	1
polyform/easy_iszero	0.14 k allocs: 4.83 kB	0.14 k allocs: 4.83 kB	1
polyform/isone	8.88 k allocs: 0.583 MB	8.88 k allocs: 0.583 MB	1
polyform/isone:noop	2 allocs: 32 B	2 allocs: 32 B	1
polyform/iszero	7.42 k allocs: 0.482 MB	7.4 k allocs: 0.481 MB	1
polyform/iszero:noop	2 allocs: 32 B	2 allocs: 32 B	1
polyform/simplify_fractions	10.1 k allocs: 0.623 MB	10.1 k allocs: 0.623 MB	1
time_to_load	0.153 k allocs: 14.5 kB	0.153 k allocs: 14.5 kB	1

[github-actions]

Benchmark Results (Julia v1)

Time benchmarks

	master	6d5a680...	master / 6d5a680...
arithmetic/addition	0.0674 ± 0.00068 ms	0.0681 ± 0.00081 ms	0.99 ± 0.015
arithmetic/division	28.1 ± 0.57 μs	27.8 ± 0.74 μs	1.01 ± 0.034
arithmetic/multiplication	0.0509 ± 0.0018 ms	0.0503 ± 0.0012 ms	1.01 ± 0.044
overhead/acrule/a+2	2.85 ± 0.089 μs	2.85 ± 0.061 μs	1 ± 0.038
overhead/acrule/a+2+b	0.09 ± 0.009 μs	0.09 ± 0.01 μs	1 ± 0.15
overhead/acrule/a+b	5.12 ± 0.17 μs	5.12 ± 0.13 μs	1 ± 0.042
overhead/acrule/noop:Int	30 ± 0 ns	30 ± 0 ns	1 ± 0
overhead/acrule/noop:Sym	0.071 ± 0.01 μs	0.07 ± 0.01 μs	1.01 ± 0.2
overhead/get_degrees/large_poly	0.0941 ± 0.007 s	0.0951 ± 0.0029 s	0.99 ± 0.079
overhead/rule/noop:Int	0.07 ± 0.01 μs	0.07 ± 0.01 μs	1 ± 0.2
overhead/rule/noop:Sym	0.07 ± 0 μs	0.07 ± 0 μs	1 ± 0
overhead/rule/noop:Term	0.07 ± 0 μs	0.07 ± 0 μs	1 ± 0
overhead/ruleset/noop:Int	30 ± 0 ns	30 ± 0 ns	1 ± 0
overhead/ruleset/noop:Sym	0.311 ± 0.01 μs	0.31 ± 0.01 μs	1 ± 0.046
overhead/ruleset/noop:Term	1.21 ± 0.02 μs	1.2 ± 0.02 μs	1.01 ± 0.024
overhead/simplify/noop:Int	30 ± 0 ns	30 ± 0 ns	1 ± 0
overhead/simplify/noop:Sym	0.07 ± 0.001 μs	0.07 ± 0.01 μs	1 ± 0.14
overhead/simplify/noop:Term	0.0328 ± 0.00067 ms	0.0329 ± 0.00071 ms	0.998 ± 0.03
overhead/simplify/randterm (+, *):serial	0.319 ± 0.045 s	0.312 ± 0.058 s	1.02 ± 0.24
overhead/simplify/randterm (+, *):thread	0.342 ± 0.028 s	0.337 ± 0.016 s	1.02 ± 0.096
overhead/simplify/randterm (/, *):serial	0.0923 ± 0.0082 ms	0.0935 ± 0.0085 ms	0.988 ± 0.13
overhead/simplify/randterm (/, *):thread	0.101 ± 0.011 ms	0.104 ± 0.01 ms	0.976 ± 0.15
overhead/substitute/a	0.043 ± 0.00078 ms	0.043 ± 0.00086 ms	0.999 ± 0.027
overhead/substitute/a,b	0.0549 ± 0.0011 ms	0.0548 ± 0.0011 ms	1 ± 0.028
overhead/substitute/a,b,c	0.0518 ± 0.00088 ms	0.0518 ± 0.001 ms	1 ± 0.026
polyform/easy_iszero	19.9 ± 0.4 μs	20 ± 0.39 μs	0.996 ± 0.028
polyform/isone	0.956 ± 0.017 ms	0.973 ± 0.015 ms	0.983 ± 0.023
polyform/isone:noop	0.15 ± 0.001 μs	0.15 ± 0.001 μs	1 ± 0.0094
polyform/iszero	0.833 ± 0.013 ms	0.842 ± 0.015 ms	0.989 ± 0.023
polyform/iszero:noop	0.151 ± 0.01 μs	0.15 ± 0.001 μs	1.01 ± 0.067
polyform/simplify_fractions	1.07 ± 0.026 ms	1.08 ± 0.03 ms	0.988 ± 0.037
time_to_load	1.25 ± 0.013 s	1.32 ± 0.012 s	0.947 ± 0.013

Memory benchmarks

	master	6d5a680...	master / 6d5a680...
arithmetic/addition	0.3 k allocs: 10.3 kB	0.3 k allocs: 10.3 kB	1
arithmetic/division	0.189 k allocs: 6.43 kB	0.189 k allocs: 6.43 kB	1
arithmetic/multiplication	0.253 k allocs: 6.47 kB	0.253 k allocs: 6.47 kB	1
overhead/acrule/a+2	0.035 k allocs: 1.13 kB	0.035 k allocs: 1.13 kB	1
overhead/acrule/a+2+b	0 allocs: 0 B	0 allocs: 0 B
overhead/acrule/a+b	0.048 k allocs: 1.56 kB	0.048 k allocs: 1.56 kB	1
overhead/acrule/noop:Int	0 allocs: 0 B	0 allocs: 0 B
overhead/acrule/noop:Sym	0 allocs: 0 B	0 allocs: 0 B
overhead/get_degrees/large_poly	0.601 M allocs: 18.4 MB	0.601 M allocs: 18.4 MB	1
overhead/rule/noop:Int	2 allocs: 0.0625 kB	2 allocs: 0.0625 kB	1
overhead/rule/noop:Sym	2 allocs: 0.0625 kB	2 allocs: 0.0625 kB	1
overhead/rule/noop:Term	2 allocs: 0.0625 kB	2 allocs: 0.0625 kB	1
overhead/ruleset/noop:Int	0 allocs: 0 B	0 allocs: 0 B
overhead/ruleset/noop:Sym	3 allocs: 0.109 kB	3 allocs: 0.109 kB	1
overhead/ruleset/noop:Term	12 allocs: 0.391 kB	12 allocs: 0.391 kB	1
overhead/simplify/noop:Int	0 allocs: 0 B	0 allocs: 0 B
overhead/simplify/noop:Sym	1 allocs: 0.0625 kB	1 allocs: 0.0625 kB	1
overhead/simplify/noop:Term	0.377 k allocs: 13.8 kB	0.377 k allocs: 13.8 kB	1
overhead/simplify/randterm (+, *):serial	4.3 M allocs: 0.144 GB	4.29 M allocs: 0.144 GB	1
overhead/simplify/randterm (+, *):thread	4.2 M allocs: 0.297 GB	4.19 M allocs: 0.297 GB	1
overhead/simplify/randterm (/, *):serial	0.794 k allocs: 28.4 kB	0.794 k allocs: 28.4 kB	1
overhead/simplify/randterm (/, *):thread	0.949 k allocs: 0.0332 MB	0.949 k allocs: 0.0332 MB	1
overhead/substitute/a	0.248 k allocs: 8.45 kB	0.248 k allocs: 8.45 kB	1
overhead/substitute/a,b	0.334 k allocs: 11.4 kB	0.334 k allocs: 11.4 kB	1
overhead/substitute/a,b,c	0.334 k allocs: 11.2 kB	0.334 k allocs: 11.2 kB	1
polyform/easy_iszero	0.106 k allocs: 3.5 kB	0.106 k allocs: 3.5 kB	1
polyform/isone	12.2 k allocs: 0.622 MB	12.1 k allocs: 0.599 MB	1.04
polyform/isone:noop	2 allocs: 32 B	2 allocs: 32 B	1
polyform/iszero	9.94 k allocs: 0.516 MB	9.92 k allocs: 0.492 MB	1.05
polyform/iszero:noop	2 allocs: 32 B	2 allocs: 32 B	1
polyform/simplify_fractions	13.2 k allocs: 0.658 MB	13.2 k allocs: 0.634 MB	1.04
time_to_load	0.145 k allocs: 11 kB	0.145 k allocs: 11 kB	1