diff --git a/stl/smooth_robustness.py b/stl/smooth_robustness.py
index 6fcf669..4082489 100644
--- a/stl/smooth_robustness.py
+++ b/stl/smooth_robustness.py
@@ -13,7 +13,7 @@ from stl.ast import t_sym
 from stl.utils import walk
 from stl.robustness import op_lookup
 
-Param = namedtuple("Param", ["L", "h", "B", "id_map"])
+Param = namedtuple("Param", ["L", "h", "B", "id_map", "eps"])
 
 @singledispatch
 def node_base(_, _1, _2):
@@ -36,17 +36,37 @@ def sample_rate(eps, L):
 
 
 def admissible_params(phi, eps, L):
+    h = sample_rate(eps, L),
+    B = max(node_base(n, eps, L) for n in walk(phi)),
+    return B, h
+
+def symbolic_params(phi, eps, L):
     return Param(
-        L=L,
-        h=sample_rate(eps, L),
-        B=max(node_base(n, eps, L) for n in walk(phi)),
-        id_map={n:i for i, n in enumerate(walk(phi))}
+        L=sym.Symbol("L"),
+        h=sym.Symbol("h"),
+        B="B",
+        id_map={n:i for i, n in enumerate(walk(phi))},
+        eps=sym.symbol("eps")
     )
 
 
-def smooth_robustness(phi, eps, L):
-    p = admissible_params(phi, eps, L)
+def smooth_robustness(phi, *, L=None, eps=None):
+    # TODO: Return symbollic formula if flag
+    p = symbolic_params(phi, eps, L)
     lo, hi = beta(phi, p), alpha(phi, p)
+    subs = {}
+    if L is not None:
+        subs[p.L] = L
+    if eps is not None:
+        subs[p.eps] = eps
+    if L is not None and eps is not None:
+        B, h = admissible_params(phi, eps, L)
+        subs[p.B] = B
+        subs[p.h] = h
+        lo, hi = lo.subs(subs), hi.subs(subs)
+    else:
+        B = p.B
+
     return sym.log(lo, B), sym.log(hi, B)