15.5 Converting among Matrix, Vector, and Array Types

There is no automatic conversion among matrices, vectors, and arrays in Stan. But there are a wide range of conversion functions to convert a matrix into a vector, or a multi-dimensional array into a one-dimensional array, or convert a vector to an array. See the section on mixed matrix and array operations in the functions reference manual for a complete list of conversion operators and the multi-indexing chapter for some reshaping operations involving multiple indexing and range indexing.