Calculate the TF for single security

tf_qt_cal(qt_ptr, names, from_to)

Arguments

qt_ptr	An R external pointer generated by `tf_quote_xptr()`.
names	A character vector in which all the elements are registered.
from_to	A length two `Date` vector whose first element must be smaller than or equal to the first.

An xts object in which the columns are the factors' value.