log M(T) for each failure rate function, as a brms expression string

Each entry is the expression string of log M(T) for one function of M_catalogue, which brms uses to build the model formula. The strings are written in terms of the parameter names and the data columns Ta (the row's temperature: the interval midpoint, or the temperature at the moment of a known-time failure) and Tr (the reference temperature of the model; see M_catalogue). The threshold functions add a small constant inside a logarithm so it stays finite at the critical temperature. The constant is written 10^-12 and not 1e-12, because brms spaces out the minus sign of a number in scientific notation when it writes the Stan program (1e - 12), which Stan does not accept. The temperature column is named Ta rather than Kingsolver and Umbanhowar's T, because T is an alias for TRUE in R and a column of that name would silently shadow it in the data-handling code. The threshold functions also reference k_sw, the softening steepness, taken from the k_sw field of M_catalogue when the model formula is built by brms. The strings are the single shared definition that fitting, simulation and reporting all evaluate.

Usage

brms_log_M

Format

A named list, one expression string per failure rate function of M_catalogue.