google
n+1-1 in sum/prod
Currently the analyzer of sum and prod does not recognize the reducable addition and subtraction in the stop parameter of range:
It would be good if we could get $n$ rather than $n+1-1$ in most cases. This reduction would be safe because the operands of range must be integers, whose objects must be always associative and commutative in terms of operations $+$ and $-$.
Note that in general arithmetic is not associative even if all operands are numbers. For example:
So this treatment is available only when the function always takes integers.
Implemented here:
https://github.com/google/latexify_py/blob/c6c291d3bcce28a269d175be384ab955ac2100c8/src/latexify/codegen/function_codegen.py#L335-L354
Current behavior is caused by not being able to convert n+1 to a numeric type.
The n+1 case can perhaps be treated as a special case since it is the most common but a more general solution might be preferred. Since reduction is only needed for n+x or n-x maybe we can explicitly check for these two cases.
@Casper-Guo I think the code above is an obsolete permalink. In the current implementation, FunctionCodegen introduced an additional analyzer that obtains subtree of range:
https://github.com/google/latexify_py/blob/071a12d06ae67c578f92f973945c0067b3f4976d/src/latexify/codegen/function_codegen.py#L334
We can implement a specific process if we detected range_info.stop is BinOp and the operator is Add or Sub.
@Casper-Guo Thanks for taking your effort! Assigned to you anyway since you are the only person who attended this discussion.