even() function for permutations

[dan mcveagh]

Hello Numas Users

Can anyone help me understand what is going on in the screenshot below?

sigma3=(1,5,2,6,4) is a single 5-cycle and therefore an even permutation.

But sig3_even=even(sigma3) returns false.

Similarly when sigma3=(1,4,3,7,2,5), which should be odd, sig3_even is true.

But for some permutations (not single cycles), the even() fuction seems to behave correctly.

What am I missing?

Thanks,

Dan

`

[Christian Lawson-Perfect]

I think my code was just wrong, sorry. I had a look at it and couldn't work out what I meant by it. I've replaced it with a routine that I'm fairly sure is correct now. Please have a look yourself and tell me if you spot any other errors.

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