Add, subtract, multiply, or divide DCP optimization problems.
# S4 method for class 'Problem,missing'
e1 + e2
# S4 method for class 'Problem,missing'
e1 - e2
# S4 method for class 'Problem,numeric'
e1 + e2
# S4 method for class 'numeric,Problem'
e1 + e2
# S4 method for class 'Problem,Problem'
e1 + e2
# S4 method for class 'Problem,numeric'
e1 - e2
# S4 method for class 'numeric,Problem'
e1 - e2
# S4 method for class 'Problem,Problem'
e1 - e2
# S4 method for class 'Problem,numeric'
e1 * e2
# S4 method for class 'numeric,Problem'
e1 * e2
# S4 method for class 'Problem,numeric'
e1/e2
A Problem object.