From 8fca19fee4cf75897d0be49912d1b369e0b6665c Mon Sep 17 00:00:00 2001
From: Tom Pollard <tpollard@mit.edu>
Date: Sun, 8 Nov 2026 15:41:29 -0500
Subject: [PATCH] Reject negative infinity in expanded signals in
 calc_adc_params

The inf check for e_p_signal only compared the channel minimum and
maximum against math.inf, so a channel containing -inf got past it and
failed later with "cannot convert float NaN to integer". Use math.isinf
so both signs are caught, as the p_signal branch already does.
---
 changelog.d/adc-negative-inf.rst |  2 ++
 src/wfdb/io/_signal.py           |  4 +---
 tests/test_record.py             | 13 +++++++++++++
 3 files changed, 16 insertions(+), 3 deletions(-)
 create mode 100644 changelog.d/adc-negative-inf.rst

diff --git a/changelog.d/adc-negative-inf.rst b/changelog.d/adc-negative-inf.rst
new file mode 100644
index 00000000..6918577e
--- /dev/null
+++ b/changelog.d/adc-negative-inf.rst
@@ -0,0 +1,2 @@
+**Reject negative infinity in expanded signals**
+  ``calc_adc_params`` now raises "Signal contains inf" when ``e_p_signal`` contains ``-inf``, as it already did for ``p_signal``, instead of failing with ``cannot convert float NaN to integer``.
diff --git a/src/wfdb/io/_signal.py b/src/wfdb/io/_signal.py
index 9b5e4dc8..f83c3c88 100644
--- a/src/wfdb/io/_signal.py
+++ b/src/wfdb/io/_signal.py
@@ -845,9 +845,7 @@ def calc_adc_params(self):
                 minvals.append(float(np.nanmin(ch)))
                 maxvals.append(float(np.nanmax(ch)))
 
-            if any(x == math.inf for x in minvals) or any(
-                x == math.inf for x in maxvals
-            ):
+            if any(math.isinf(x) for x in minvals + maxvals):
                 raise ValueError("Signal contains inf. Cannot perform adc.")
 
             for ch, _ in enumerate(self.e_p_signal):
diff --git a/tests/test_record.py b/tests/test_record.py
index 788a9abe..55f8415d 100644
--- a/tests/test_record.py
+++ b/tests/test_record.py
@@ -1513,6 +1513,19 @@ def test_physical_conversion(self, temp_path):
                     atol=(0.05 / gain),
                 )
 
+    @pytest.mark.parametrize("value", [np.inf, -np.inf])
+    @pytest.mark.parametrize("expanded", [False, True])
+    def test_adc_params_inf(self, value, expanded):
+        """Reject signals containing positive or negative infinity."""
+        p_signal = np.array([[1.0, 0.5], [value, -0.25]])
+        if expanded:
+            record = wfdb.Record(e_p_signal=list(p_signal.T), fmt=["16", "16"])
+        else:
+            record = wfdb.Record(p_signal=p_signal, fmt=["16", "16"])
+
+        with pytest.raises(ValueError, match="Signal contains inf"):
+            record.calc_adc_params()
+
     def test_adc_gain_max_boundary(self, temp_path):
         """Exercise the MAX_I32 clamp path.