Install slicot in CI workflows, add slycot fallback

jamestjsp · claude · jamestjsp · commit 41f9bf0dea92 · 2026-01-31T10:21:39.000-06:00
- Update doctest.yml and install_examples.yml to install slicot via pip
- Modify slicot_compat.py to fall back to slycot if slicot unavailable
- Update slicot_check() to detect either package

Addresses PR review comments: install slicot in workflows and support
both slicot and slycot for backwards compatibility.

Co-Authored-By: Claude Opus 4.5 &lt;noreply@anthropic.com&gt;
diff --git a/.github/workflows/doctest.yml b/.github/workflows/doctest.yml
@@ -27,7 +27,8 @@ jobs:
     - name: Install full dependencies
       shell: bash -l {0}
       run: |
-        mamba install cvxopt pandas slycot 
+        mamba install cvxopt pandas
+        pip install slicot 
 
     - name: Run doctest
       shell: bash -l {0}
diff --git a/.github/workflows/install_examples.yml b/.github/workflows/install_examples.yml
@@ -20,8 +20,9 @@ jobs:
            --quiet --yes \
            python=3.12 pip \
            numpy matplotlib scipy \
-           slycot pmw jupyter \
+           pmw jupyter \
            ipython!=9.0
+        conda run -n control-examples-env pip install slicot
 
     - name: Install from source
       run: |
diff --git a/control/exception.py b/control/exception.py
@@ -47,17 +47,21 @@ class ControlNotImplemented(NotImplementedError):
     """Functionality is not yet implemented."""
     pass
 
-# Utility function to see if slicot is installed
+# Utility function to see if slicot or slycot is installed
 slicot_installed = None
 def slicot_check():
-    """Return True if slicot is installed, otherwise False."""
+    """Return True if slicot or slycot is installed, otherwise False."""
     global slicot_installed
     if slicot_installed is None:
         try:
             import slicot  # noqa: F401
             slicot_installed = True
-        except:
-            slicot_installed = False
+        except ImportError:
+            try:
+                import slycot  # noqa: F401
+                slicot_installed = True
+            except ImportError:
+                slicot_installed = False
     return slicot_installed
 
 
diff --git a/control/slicot_compat.py b/control/slicot_compat.py
@@ -1,20 +1,37 @@
-# slicot_compat.py - compatibility wrappers for slicot package
+# slicot_compat.py - compatibility wrappers for slicot/slycot packages
 #
 # This module provides wrappers around the slicot package functions to match
-# the API used by the older slycot package. This allows python-control to
-# use slicot (C11 translation with Python bindings) as a drop-in replacement.
+# the API used by the older slycot package. It also supports falling back to
+# slycot if slicot is not installed.
 
-"""Compatibility layer for slicot package.
+"""Compatibility layer for slicot/slycot packages.
 
 This module wraps slicot functions to match the slycot API, minimizing changes
-to existing code in python-control.
+to existing code in python-control. If slicot is not installed, it falls back
+to using slycot directly.
 """
 
-import slicot  # noqa: F401 - import at top level so ImportError is raised early
 import numpy as np
 
 from .exception import ControlArgument
 
+# Try to import slicot first (preferred), fall back to slycot
+_use_slicot = False
+_use_slycot = False
+
+try:
+    import slicot  # noqa: F401
+    _use_slicot = True
+except ImportError:
+    try:
+        import slycot  # noqa: F401
+        _use_slycot = True
+    except ImportError:
+        pass
+
+if not _use_slicot and not _use_slycot:
+    raise ImportError("Neither slicot nor slycot is installed")
+
 __all__ = [
     'SlicotResultWarning', 'SlicotArithmeticError',
     'sb03md', 'sb03od', 'sb04md', 'sb04qd', 'sg03ad',
@@ -1087,3 +1104,19 @@ def mb03rd(n, A, X, pmax=1.0, tol=0.0, ldwork=None):
     w = wr + 1j * wi
 
     return Aout, Xout, blsize[:nblcks], w
+
+
+# If using slycot (not slicot), overwrite with direct imports from slycot
+if _use_slycot and not _use_slicot:
+    from slycot import (  # noqa: F811
+        sb03md, sb03od, sb04md, sb04qd, sg03ad,
+        sb02md, sb02mt, sg02ad, sb01bd,
+        sb10ad, sb10hd, ab08nd,
+        ab09ad, ab09md, ab09nd,
+        ab13bd, ab13dd, ab13md,
+        tb01pd, tb04ad, tb05ad, td04ad, mb03rd,
+    )
+    from slycot.exceptions import (  # noqa: F811
+        SlycotResultWarning as SlicotResultWarning,
+        SlycotArithmeticError as SlicotArithmeticError,
+    )
