halfway merged and pulled?!

projects/ML_based_MLSE/interp_fec_cross.m

@@ -0,0 +1,13 @@
+function rop_fec = interp_fec_cross(rops, ber, fec_thr)
+    if all(~isfinite(ber))
+        rop_fec = NaN; return;
+    end
+    idx = find(ber < fec_thr, 1, 'first');
+    if isempty(idx) || idx == 1
+        rop_fec = NaN; return; % no crossing
+    end
+    % linear interpolation between the two nearest points
+    x1 = rops(idx-1); x2 = rops(idx);
+    y1 = ber(idx-1);  y2 = ber(idx);
+    rop_fec = interp1([y1 y2], [x1 x2], fec_thr, 'linear', NaN);
+end