jax.scipy.linalg.solve: deprecate the sym_pos argument following scipy 1.9.0

CHANGELOG.md

@@ -26,6 +26,8 @@ PLEASE REMEMBER TO CHANGE THE '..main' WITH AN ACTUAL TAG in GITHUB LINK.
     * {func}`jax.tree_structure` is deprecated in favor of {func}`jax.tree_util.tree_structure`
     * {func}`jax.tree_transpose` is deprecated in favor of {func}`jax.tree_util.tree_transpose`
     * {func}`jax.tree_unflatten` is deprecated in favor of {func}`jax.tree_util.tree_unflatten`
+  * The `sym_pos` argument of {func}`jax.scipy.linalg.solve` is deprecated in favor of `assume_a='pos'`,
+    following a similar deprecation in {func}`scipy.linalg.solve`.
 
 ## jaxlib 0.3.15 (Unreleased)
 

jax/_src/scipy/linalg.py

@@ -205,9 +205,9 @@ def qr(a, overwrite_a=False, lwork=None, mode="full", pivoting=False,
   return _qr(a, mode, pivoting)
 
 
-@partial(jit, static_argnames=('sym_pos', 'lower'))
-def _solve(a, b, sym_pos, lower):
-  if not sym_pos:
+@partial(jit, static_argnames=('assume_a', 'lower'))
+def _solve(a, b, assume_a, lower):
+  if assume_a != 'pos':
     return np_linalg.solve(a, b)
 
   a, b = _promote_dtypes_inexact(jnp.asarray(a), jnp.asarray(b))
@@ -232,9 +232,18 @@ def _solve(a, b, sym_pos, lower):
 @_wraps(scipy.linalg.solve,
         lax_description=_no_overwrite_and_chkfinite_doc, skip_params=('overwrite_a', 'overwrite_b', 'debug', 'check_finite'))
 def solve(a, b, sym_pos=False, lower=False, overwrite_a=False, overwrite_b=False,
-          debug=False, check_finite=True):
+          debug=False, check_finite=True, assume_a='gen'):
+  # TODO(jakevdp) remove sym_pos argument after October 2022
   del overwrite_a, overwrite_b, debug, check_finite
-  return _solve(a, b, sym_pos, lower)
+  valid_assume_a = ['gen', 'sym', 'her', 'pos']
+  if assume_a not in valid_assume_a:
+    raise ValueError("Expected assume_a to be one of {valid_assume_a}; got {assume_a!r}")
+  if sym_pos:
+    warnings.warn("The sym_pos argument to solve() is deprecated and will be removed "
+                  "in a future JAX release. Use assume_a='pos' instead.",
+                  category=FutureWarning, stacklevel=2)
+    assume_a = 'pos'
+  return _solve(a, b, assume_a, lower)
 
 @partial(jit, static_argnames=('trans', 'lower', 'unit_diagonal'))
 def _solve_triangular(a, b, trans, lower, unit_diagonal):

jax/_src/scipy/sparse/linalg.py

@@ -512,7 +512,7 @@ def _lstsq(a, b):
   # faster than jsp.linalg.lstsq
   a2 = _dot(a.T.conj(), a)
   b2 = _dot(a.T.conj(), b)
-  return jsp.linalg.solve(a2, b2, sym_pos=True)
+  return jsp.linalg.solve(a2, b2, assume_a='pos')
 
 
 def _gmres_batched(A, b, x0, unit_residual, residual_norm, ptol, restart, M):

tests/linalg_test.py

@@ -1153,31 +1153,31 @@ class ScipyLinalgTest(jtu.JaxTestCase):
 
   @parameterized.named_parameters(jtu.cases_from_list(
       {"testcase_name":
-       "_lhs={}_rhs={}_sym_pos={}_lower={}".format(
+       "_lhs={}_rhs={}_assume_a={}_lower={}".format(
            jtu.format_shape_dtype_string(lhs_shape, dtype),
            jtu.format_shape_dtype_string(rhs_shape, dtype),
-           sym_pos, lower),
+           assume_a, lower),
        "lhs_shape": lhs_shape, "rhs_shape": rhs_shape, "dtype": dtype,
-       "sym_pos": sym_pos, "lower": lower}
+       "assume_a": assume_a, "lower": lower}
       for lhs_shape, rhs_shape in [
           ((1, 1), (1, 1)),
           ((4, 4), (4,)),
           ((8, 8), (8, 4)),
       ]
-      for sym_pos, lower in [
-        (False, False),
-        (True, False),
-        (True, True),
+      for assume_a, lower in [
+        ('gen', False),
+        ('pos', False),
+        ('pos', True),
       ]
       for dtype in float_types + complex_types))
-  def testSolve(self, lhs_shape, rhs_shape, dtype, sym_pos, lower):
+  def testSolve(self, lhs_shape, rhs_shape, dtype, assume_a, lower):
     rng = jtu.rand_default(self.rng())
-    osp_fun = lambda lhs, rhs: osp.linalg.solve(lhs, rhs, sym_pos=sym_pos, lower=lower)
-    jsp_fun = lambda lhs, rhs: jsp.linalg.solve(lhs, rhs, sym_pos=sym_pos, lower=lower)
+    osp_fun = lambda lhs, rhs: osp.linalg.solve(lhs, rhs, assume_a=assume_a, lower=lower)
+    jsp_fun = lambda lhs, rhs: jsp.linalg.solve(lhs, rhs, assume_a=assume_a, lower=lower)
 
     def args_maker():
       a = rng(lhs_shape, dtype)
-      if sym_pos:
+      if assume_a == 'pos':
         a = np.matmul(a, np.conj(T(a)))
         a = np.tril(a) if lower else np.triu(a)
       return [a, rng(rhs_shape, dtype)]