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maxima

Select the elements at even indexes in maxima

In maxima, "sublist" allows you to select certain elements of a list with different criterions. I'd like to select the elements at even indexes. I've thought about something like

sublist([1,2,4,5,7,8],evenp(sublist_indices()));

but obviously it doesn't work. How can I do it without writing down a for loop?

Solution

  • Well, how about something like:

    (%i2) L : [a, b, c, d, e, f, g];
(%o2)                        [a, b, c, d, e, f, g]
(%i3) makelist (L[2*i], i, 1, floor (length(L) / 2));
(%o3)                              [b, d, f]