Is `expression(alpha)` (used in plotting) a “unevaluated expression”? How?

Question

In order to write Greek letters / math on plot axes , we can use expression(alpha) . Is this the same as an unevaluated expression, as defined here ? I don't see the connection between the two. Shouldn't expression(alpha) returns the unevaluated expression alpha ? How did it become the symbol $\\alpha$?

Answer 1

No. This returns just alpha :

quote(alpha)

An expression vector should be thought of as a type of list. The plotmath interpreter is set up to be a plotting subset of something like LaTeX, but in a much more limited way. Review these pages:

 ?plotmath # really need to work through the examples; one by one
 ?bquote   # exceedingly useful ...  except with lattice functions
 ?substitute   # several of the plotmath examples need `substitute`
 ?points   # the example at the end.