extern const struct x1f4_function_type *const x1f4_e4_computables;
x1f4_e4_computables points to an array of always computable functions.
The array is null terminated (the last
definition in the array has its
name field set as
x1f4_e4_computables points into
x1f4_e4_defaults and excludes
functions that depending their arguments may fail to evaluate (such as
log and sqrt that are defined for positive input only).