Range checking.

src/Data/Find/Interpolation.hs

@@ -24,14 +24,13 @@ search r j' (rmin, rmax) t =
       traceShowM (l, h)
       vl <- r l
       vh <- r h
-      let m = (l%1) + (((j t) - (j vl)) * ((h%1) - (l%1)) / ((j vh) - (j vl)))
+      let m = max l $ min h $ floor $ (l%1) + (((j t) - (j vl)) * ((h%1) - (l%1)) / ((j vh) - (j vl)))
       -- This reads the m value even if we can't find the result there.
-      let mi = floor m
-      vm <- r mi
-      traceShowM [ ("l", show l), ("m", show m), ("mi", show mi), ("h", show h)
+      vm <- r m
+      traceShowM [ ("l", show l), ("m", show m), ("h", show h)
                  , ("vl", show vl), ("vm", show vm), ("vh", show vh)]
       if | not ((vh /= vl) && (t >= vl) && (t <= vh)) -> pure Nothing
-         | vm < t  -> go (mi+1) h
-         | t < vm  -> go l     (mi-1)
-         | vm == t -> pure $ Just mi
+         | vm < t  -> go (m+1) h
+         | t < vm  -> go l     (m-1)
+         | vm == t -> pure $ Just m
          | vm /= t -> pure Nothing