is.formula

an R object to be tested.

<code>is.formula</code> returns <code>TRUE</code> if <code>x</code> is an object of
 class <code>"formula"</code>, and <code>FALSE</code> otherwise.

utilities

Routines and documentation for solving regression problems
while imposing an L1 constraint on the estimates, based on
the algorithm of Osborne et al. (1998).

Berwin Turlach

is.formula: Tests for Formula Objects

Description

Usage

Arguments