diff --git a/src/evox/problems/numerical/maf.py b/src/evox/problems/numerical/maf.py
index 98a893619..50b283970 100644
--- a/src/evox/problems/numerical/maf.py
+++ b/src/evox/problems/numerical/maf.py
@@ -12,7 +12,7 @@
 @jit
 def inside(x, a, b):
     """check if x is in [a, b] or [b, a]"""
-    return (a <= x <= b) | (b <= x <= a)
+    return (jnp.minimum(a, b) <= x) & (x <= jnp.maximum(a, b))
 
 
 @jit
@@ -33,7 +33,7 @@ def ray_intersect_segment(point, seg_init, seg_term):
     judge_2 = (LHS >= RHS) ^ (y_dist < 0)
     # check intersection_y, which is P_y is inside the segment
     judge_3 = inside(point[1], seg_init[1], seg_term[1])
-    return ((y_dist == 0) & judge_1) | (y_dist != 0 & judge_2 & judge_3)
+    return ((y_dist == 0) & judge_1) | ((y_dist != 0) & judge_2 & judge_3)
 
 
 @jit