Changes between Initial Version and Version 1 of Ticket #20469, comment 8


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Timestamp:
07/12/16 23:25:14 (5 years ago)
Author:
andrew.mathas
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  • Ticket #20469, comment 8

    initial v1  
    11Hi Travis,
    22
    3 I have been through your code and fixed the recursion issue. It was actually an infinite recursion loop. The problem was that as the terms in the products `....T_i L_k...` were being put into standard form "letter-by-letter" (so changing the previous expression to `\sum ... L_m T_j...`) you sometimes ended up going around in circles by pushing a `T_i` past an `L_k` that then created a large power of some `L_m` that, when reduced, got you back to the previous situation. I have rewritten the `product_on_basis` code to avoid this, so I'm afraid that I've replaced this section of your code. he product code is now less recursive with terms largely being rewritten into standard form "in place".
     3I have been through your code and fixed the recursion issue. It was actually an infinite recursion loop. The problem was that as the terms in the products `....T_i L_k...` were being put into standard form "letter-by-letter" (so changing the previous expression to `\sum ... L_m T_j...`) you sometimes ended up going around in circles by pushing a `T_i` past an `L_k` that then created a large power of some `L_m` that, when reduced, got you back to the previous situation. I have rewritten the `product_on_basis` code to avoid this, so I'm afraid that I've replaced this section of your code. The product code is now less recursive with terms largely being rewritten into standard form "in place".
    44
    55On top of this I proved a formula for the expansion of `L_k^m` tat, embarrassingly, I later found in one of my papers. This was my first guess for improving the multiplication issues but once I'd made this change I discovered the recursion loop. The other main change is that I changed `L_k` to `q**{1-k}*L_k` because this renormalisation is what is normally used in the literature as it works better with the combinatorics.