Concatenating N vectors

General
21

How come that dims(.) yields an array of length 3, and why does my code even compile? Isn’t this a bug?

22

I believe dims is treating the vector input like a matrix, so the returned dims array represents:

  1. Array length
  2. Number of rows
  3. Number of cols

The lack of compiler error is a longstanding issue where the compiler allows assigning vectors of different lengths: Assignment to vector of different size currently allowed · Issue #523 · stan-dev/stanc3 · GitHub

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