We present a price-directive decomposition algorithm to compute an approximate solution of the mixed packing and covering
problem; it either finds
x ∈
B such that
f(
x) ≤
c(1 +
ε)
a and
g(
x) ≥ (1 −
ε)
b/
c or correctly decides that {
x ∈
B|
f(
x) ≤
a,
g(
x) ≥
b} = ∅. Here
f,
g are vectors of
M ≥ 2 convex and concave functions, respectively, which are nonnegative on the convex compact set ∅ ≠
B ⊆ ℝ
N
;
B can be queried by a feasibility oracle or
block solver,
a,

and
c is the block solver’s approximation ratio. The algorithm needs only
O(
M(ln
M +
ε
− 2 ln
ε
− 1)) iterations, a runtime bound independent from
c and the input data. Our algorithm is a generalization of [16] and also approximately solves the fractional packing and covering
problem where
f,
g are linear and
B is a polytope; there, a
width-independent runtime bound is obtained.