Fix reference implementations for complex elementwise functions

Some of these still have some issues that need to be addressed, like
overflows.

Author: asmeurer

Diff for: array_api_tests/test_operators_and_elementwise_functions.py

@@ -703,9 +703,9 @@ def test_abs(ctx, data):
         abs,  # type: ignore
         res_stype=float if x.dtype in dh.complex_dtypes else None,
         expr_template="abs({})={}",
-        filter_=lambda s: (
-            s == float("infinity") or (math.isfinite(s) and not ph.is_neg_zero(s))
-        ),
+        # filter_=lambda s: (
+        #     s == float("infinity") or (cmath.isfinite(s) and not ph.is_neg_zero(s))
+        # ),
     )
 
 
@@ -714,8 +714,10 @@ def test_acos(x):
     out = xp.acos(x)
     ph.assert_dtype("acos", in_dtype=x.dtype, out_dtype=out.dtype)
     ph.assert_shape("acos", out_shape=out.shape, expected=x.shape)
+    refimpl = cmath.acos if x.dtype in dh.complex_dtypes else math.acos
+    filter_ = default_filter if x.dtype in dh.complex_dtypes else lambda s: default_filter(s) and -1 <= s <= 1
     unary_assert_against_refimpl(
-        "acos", x, out, math.acos, filter_=lambda s: default_filter(s) and -1 <= s <= 1
+        "acos", x, out, refimpl, filter_=filter_
     )
 
 
@@ -724,8 +726,10 @@ def test_acosh(x):
     out = xp.acosh(x)
     ph.assert_dtype("acosh", in_dtype=x.dtype, out_dtype=out.dtype)
     ph.assert_shape("acosh", out_shape=out.shape, expected=x.shape)
+    refimpl = cmath.acosh if x.dtype in dh.complex_dtypes else math.acosh
+    filter_ = default_filter if x.dtype in dh.complex_dtypes else lambda s: default_filter(s) and s >= 1
     unary_assert_against_refimpl(
-        "acosh", x, out, math.acosh, filter_=lambda s: default_filter(s) and s >= 1
+        "acosh", x, out, refimpl, filter_=filter_
     )
 
 
@@ -748,8 +752,10 @@ def test_asin(x):
     out = xp.asin(x)
     ph.assert_dtype("asin", in_dtype=x.dtype, out_dtype=out.dtype)
     ph.assert_shape("asin", out_shape=out.shape, expected=x.shape)
+    refimpl = cmath.asin if x.dtype in dh.complex_dtypes else math.asin
+    filter_ = default_filter if x.dtype in dh.complex_dtypes else lambda s: default_filter(s) and -1 <= s <= 1
     unary_assert_against_refimpl(
-        "asin", x, out, math.asin, filter_=lambda s: default_filter(s) and -1 <= s <= 1
+        "asin", x, out, refimpl, filter_=filter_
     )
 
 
@@ -758,36 +764,41 @@ def test_asinh(x):
     out = xp.asinh(x)
     ph.assert_dtype("asinh", in_dtype=x.dtype, out_dtype=out.dtype)
     ph.assert_shape("asinh", out_shape=out.shape, expected=x.shape)
-    unary_assert_against_refimpl("asinh", x, out, math.asinh)
+    refimpl = cmath.asinh if x.dtype in dh.complex_dtypes else math.asinh
+    unary_assert_against_refimpl("asinh", x, out, refimpl)
 
 
 @given(hh.arrays(dtype=hh.all_floating_dtypes(), shape=hh.shapes()))
 def test_atan(x):
     out = xp.atan(x)
     ph.assert_dtype("atan", in_dtype=x.dtype, out_dtype=out.dtype)
     ph.assert_shape("atan", out_shape=out.shape, expected=x.shape)
-    unary_assert_against_refimpl("atan", x, out, math.atan)
+    refimpl = cmath.atan if x.dtype in dh.complex_dtypes else math.atan
+    unary_assert_against_refimpl("atan", x, out, refimpl)
 
 
 @given(*hh.two_mutual_arrays(dh.real_float_dtypes))
 def test_atan2(x1, x2):
     out = xp.atan2(x1, x2)
     ph.assert_dtype("atan2", in_dtype=[x1.dtype, x2.dtype], out_dtype=out.dtype)
     ph.assert_result_shape("atan2", in_shapes=[x1.shape, x2.shape], out_shape=out.shape)
-    binary_assert_against_refimpl("atan2", x1, x2, out, math.atan2)
+    refimpl = cmath.atan2 if x1.dtype in dh.complex_dtypes else math.atan2
+    binary_assert_against_refimpl("atan2", x1, x2, out, refimpl)
 
 
 @given(hh.arrays(dtype=hh.all_floating_dtypes(), shape=hh.shapes()))
 def test_atanh(x):
     out = xp.atanh(x)
     ph.assert_dtype("atanh", in_dtype=x.dtype, out_dtype=out.dtype)
     ph.assert_shape("atanh", out_shape=out.shape, expected=x.shape)
+    refimpl = cmath.atanh if x.dtype in dh.complex_dtypes else math.atanh
+    filter_ = default_filter if x.dtype in dh.complex_dtypes else lambda s: default_filter(s) and -1 < s < 1
     unary_assert_against_refimpl(
         "atanh",
         x,
         out,
-        math.atanh,
-        filter_=lambda s: default_filter(s) and -1 <= s <= 1,
+        refimpl,
+        filter_=filter_,
     )
 
 
@@ -1065,15 +1076,17 @@ def test_cos(x):
     out = xp.cos(x)
     ph.assert_dtype("cos", in_dtype=x.dtype, out_dtype=out.dtype)
     ph.assert_shape("cos", out_shape=out.shape, expected=x.shape)
-    unary_assert_against_refimpl("cos", x, out, math.cos)
+    refimpl = cmath.cos if x.dtype in dh.complex_dtypes else math.cos
+    unary_assert_against_refimpl("cos", x, out, refimpl)
 
 
 @given(hh.arrays(dtype=hh.all_floating_dtypes(), shape=hh.shapes()))
 def test_cosh(x):
     out = xp.cosh(x)
     ph.assert_dtype("cosh", in_dtype=x.dtype, out_dtype=out.dtype)
     ph.assert_shape("cosh", out_shape=out.shape, expected=x.shape)
-    unary_assert_against_refimpl("cosh", x, out, math.cosh)
+    refimpl = cmath.cosh if x.dtype in dh.complex_dtypes else math.cosh
+    unary_assert_against_refimpl("cosh", x, out, refimpl)
 
 
 @pytest.mark.parametrize("ctx", make_binary_params("divide", dh.all_float_dtypes))
@@ -1097,7 +1110,7 @@ def test_divide(ctx, data):
         res,
         "/",
         operator.truediv,
-        filter_=lambda s: math.isfinite(s) and s != 0,
+        filter_=lambda s: cmath.isfinite(s) and s != 0,
     )
 
 
@@ -1134,23 +1147,45 @@ def test_exp(x):
     out = xp.exp(x)
     ph.assert_dtype("exp", in_dtype=x.dtype, out_dtype=out.dtype)
     ph.assert_shape("exp", out_shape=out.shape, expected=x.shape)
-    unary_assert_against_refimpl("exp", x, out, math.exp)
+    refimpl = cmath.exp if x.dtype in dh.complex_dtypes else math.exp
+    unary_assert_against_refimpl("exp", x, out, refimpl)
 
 
 @given(hh.arrays(dtype=hh.all_floating_dtypes(), shape=hh.shapes()))
 def test_expm1(x):
     out = xp.expm1(x)
     ph.assert_dtype("expm1", in_dtype=x.dtype, out_dtype=out.dtype)
     ph.assert_shape("expm1", out_shape=out.shape, expected=x.shape)
-    unary_assert_against_refimpl("expm1", x, out, math.expm1)
+    if x.dtype in dh.complex_dtypes:
+        def refimpl(z):
+            # There's no cmath.expm1. Use
+            #
+            # exp(x+yi) - 1
+            # = exp(x)exp(yi) - 1
+            # = exp(x)(cos(y) + sin(y)i) - 1
+            # = (exp(x) - 1)cos(y) + (cos(y) - 1) + exp(x)sin(y)i
+            # = expm1(x)cos(y) - 2sin(y/2)^2 + exp(x)sin(y)i
+            #
+            # where 1 - cos(y) = 2sin(y/2)^2 is used to avoid loss of
+            # significance near y = 0.
+            re, im = z.real, z.imag
+            return math.expm1(re)*math.cos(im) - 2*math.sin(im/2)**2 + 1j*math.exp(re)*math.sin(im)
+    else:
+        refimpl = math.expm1
+    unary_assert_against_refimpl("expm1", x, out, refimpl)
 
 
 @given(hh.arrays(dtype=hh.real_dtypes, shape=hh.shapes()))
 def test_floor(x):
     out = xp.floor(x)
     ph.assert_dtype("floor", in_dtype=x.dtype, out_dtype=out.dtype)
     ph.assert_shape("floor", out_shape=out.shape, expected=x.shape)
-    unary_assert_against_refimpl("floor", x, out, math.floor, strict_check=True)
+    if x.dtype in dh.complex_dtypes:
+        def refimpl(z):
+            return complex(math.floor(z.real), math.floor(z.imag))
+    else:
+        refimpl = math.floor
+    unary_assert_against_refimpl("floor", x, out, refimpl, strict_check=True)
 
 
 @pytest.mark.parametrize("ctx", make_binary_params("floor_divide", dh.real_dtypes))
@@ -1236,23 +1271,26 @@ def test_isfinite(x):
     out = xp.isfinite(x)
     ph.assert_dtype("isfinite", in_dtype=x.dtype, out_dtype=out.dtype, expected=xp.bool)
     ph.assert_shape("isfinite", out_shape=out.shape, expected=x.shape)
-    unary_assert_against_refimpl("isfinite", x, out, math.isfinite, res_stype=bool)
+    refimpl = cmath.isfinite if x.dtype in dh.complex_dtypes else math.isfinite
+    unary_assert_against_refimpl("isfinite", x, out, refimpl, res_stype=bool)
 
 
 @given(hh.arrays(dtype=hh.numeric_dtypes, shape=hh.shapes()))
 def test_isinf(x):
     out = xp.isinf(x)
     ph.assert_dtype("isfinite", in_dtype=x.dtype, out_dtype=out.dtype, expected=xp.bool)
     ph.assert_shape("isinf", out_shape=out.shape, expected=x.shape)
-    unary_assert_against_refimpl("isinf", x, out, math.isinf, res_stype=bool)
+    refimpl = cmath.isinf if x.dtype in dh.complex_dtypes else math.isinf
+    unary_assert_against_refimpl("isinf", x, out, refimpl, res_stype=bool)
 
 
 @given(hh.arrays(dtype=hh.numeric_dtypes, shape=hh.shapes()))
 def test_isnan(x):
     out = xp.isnan(x)
     ph.assert_dtype("isnan", in_dtype=x.dtype, out_dtype=out.dtype, expected=xp.bool)
     ph.assert_shape("isnan", out_shape=out.shape, expected=x.shape)
-    unary_assert_against_refimpl("isnan", x, out, math.isnan, res_stype=bool)
+    refimpl = cmath.isnan if x.dtype in dh.complex_dtypes else math.isnan
+    unary_assert_against_refimpl("isnan", x, out, refimpl, res_stype=bool)
 
 
 @pytest.mark.parametrize("ctx", make_binary_params("less", dh.real_dtypes))
@@ -1300,8 +1338,10 @@ def test_log(x):
     out = xp.log(x)
     ph.assert_dtype("log", in_dtype=x.dtype, out_dtype=out.dtype)
     ph.assert_shape("log", out_shape=out.shape, expected=x.shape)
+    refimpl = cmath.log if x.dtype in dh.complex_dtypes else math.log
+    filter_ = default_filter if x.dtype in dh.complex_dtypes else lambda s: default_filter(s) and s > 0
     unary_assert_against_refimpl(
-        "log", x, out, math.log, filter_=lambda s: default_filter(s) and s >= 1
+        "log", x, out, refimpl, filter_=filter_
     )
 
 
@@ -1310,8 +1350,19 @@ def test_log1p(x):
     out = xp.log1p(x)
     ph.assert_dtype("log1p", in_dtype=x.dtype, out_dtype=out.dtype)
     ph.assert_shape("log1p", out_shape=out.shape, expected=x.shape)
+    # There isn't a cmath.log1p, and implementing one isn't straightforward
+    # (see
+    # https://stackoverflow.com/questions/78318212/unexpected-behaviour-of-log1p-numpy).
+    # For now, just use log(1+p) for complex inputs, which should hopefully be
+    # fine given the very loose numerical tolerances we use. If it isn't, we
+    # can try using something like a series expansion for small p.
+    if x.dtype in dh.complex_dtypes:
+        refimpl = lambda z: cmath.log(1+z)
+    else:
+        refimpl = math.log1p
+    filter_ = default_filter if x.dtype in dh.complex_dtypes else lambda s: default_filter(s) and s > -1
     unary_assert_against_refimpl(
-        "log1p", x, out, math.log1p, filter_=lambda s: default_filter(s) and s >= 1
+        "log1p", x, out, refimpl, filter_=filter_
     )
 
 
@@ -1320,8 +1371,13 @@ def test_log2(x):
     out = xp.log2(x)
     ph.assert_dtype("log2", in_dtype=x.dtype, out_dtype=out.dtype)
     ph.assert_shape("log2", out_shape=out.shape, expected=x.shape)
+    if x.dtype in dh.complex_dtypes:
+        refimpl = lambda z: cmath.log(z)/math.log(2)
+    else:
+        refimpl = math.log2
+    filter_ = default_filter if x.dtype in dh.complex_dtypes else lambda s: default_filter(s) and s > 0
     unary_assert_against_refimpl(
-        "log2", x, out, math.log2, filter_=lambda s: default_filter(s) and s > 1
+        "log2", x, out, refimpl, filter_=filter_
     )
 
 
@@ -1330,12 +1386,17 @@ def test_log10(x):
     out = xp.log10(x)
     ph.assert_dtype("log10", in_dtype=x.dtype, out_dtype=out.dtype)
     ph.assert_shape("log10", out_shape=out.shape, expected=x.shape)
+    if x.dtype in dh.complex_dtypes:
+        refimpl = lambda z: cmath.log(z)/math.log(10)
+    else:
+        refimpl = math.log10
+    filter_ = default_filter if x.dtype in dh.complex_dtypes else lambda s: default_filter(s) and s > 0
     unary_assert_against_refimpl(
-        "log10", x, out, math.log10, filter_=lambda s: default_filter(s) and s > 0
+        "log10", x, out, refimpl, filter_=filter_
     )
 
 
-def logaddexp(l: float, r: float) -> float:
+def logaddexp_refimpl(l: float, r: float) -> float:
     return math.log(math.exp(l) + math.exp(r))
 
 
@@ -1344,7 +1405,7 @@ def test_logaddexp(x1, x2):
     out = xp.logaddexp(x1, x2)
     ph.assert_dtype("logaddexp", in_dtype=[x1.dtype, x2.dtype], out_dtype=out.dtype)
     ph.assert_result_shape("logaddexp", in_shapes=[x1.shape, x2.shape], out_shape=out.shape)
-    binary_assert_against_refimpl("logaddexp", x1, x2, out, logaddexp)
+    binary_assert_against_refimpl("logaddexp", x1, x2, out, logaddexp_refimpl)
 
 
 @given(*hh.two_mutual_arrays([xp.bool]))
@@ -1521,7 +1582,11 @@ def test_round(x):
     out = xp.round(x)
     ph.assert_dtype("round", in_dtype=x.dtype, out_dtype=out.dtype)
     ph.assert_shape("round", out_shape=out.shape, expected=x.shape)
-    unary_assert_against_refimpl("round", x, out, round, strict_check=True)
+    if x.dtype in dh.complex_dtypes:
+        refimpl = lambda z: complex(round(z.real), round(z.imag))
+    else:
+        refimpl = round
+    unary_assert_against_refimpl("round", x, out, refimpl, strict_check=True)
 
 
 @pytest.mark.min_version("2023.12")
@@ -1539,13 +1604,12 @@ def test_sign(x):
     out = xp.sign(x)
     ph.assert_dtype("sign", in_dtype=x.dtype, out_dtype=out.dtype)
     ph.assert_shape("sign", out_shape=out.shape, expected=x.shape)
-    refimpl = lambda x: x / math.abs(x) if x != 0 else 0
+    refimpl = lambda x: x / abs(x) if x != 0 else 0
     unary_assert_against_refimpl(
         "sign",
         x,
         out,
         refimpl,
-        filter_=lambda s: s != 0,
         strict_check=True,
     )
 
@@ -1555,15 +1619,17 @@ def test_sin(x):
     out = xp.sin(x)
     ph.assert_dtype("sin", in_dtype=x.dtype, out_dtype=out.dtype)
     ph.assert_shape("sin", out_shape=out.shape, expected=x.shape)
-    unary_assert_against_refimpl("sin", x, out, math.sin)
+    refimpl = cmath.sin if x.dtype in dh.complex_dtypes else math.sin
+    unary_assert_against_refimpl("sin", x, out, refimpl)
 
 
 @given(hh.arrays(dtype=hh.all_floating_dtypes(), shape=hh.shapes()))
 def test_sinh(x):
     out = xp.sinh(x)
     ph.assert_dtype("sinh", in_dtype=x.dtype, out_dtype=out.dtype)
     ph.assert_shape("sinh", out_shape=out.shape, expected=x.shape)
-    unary_assert_against_refimpl("sinh", x, out, math.sinh)
+    refimpl = cmath.sinh if x.dtype in dh.complex_dtypes else math.sinh
+    unary_assert_against_refimpl("sinh", x, out, refimpl)
 
 
 @given(hh.arrays(dtype=hh.numeric_dtypes, shape=hh.shapes()))
@@ -1581,8 +1647,10 @@ def test_sqrt(x):
     out = xp.sqrt(x)
     ph.assert_dtype("sqrt", in_dtype=x.dtype, out_dtype=out.dtype)
     ph.assert_shape("sqrt", out_shape=out.shape, expected=x.shape)
+    refimpl = cmath.sqrt if x.dtype in dh.complex_dtypes else math.sqrt
+    filter_ = default_filter if x.dtype in dh.complex_dtypes else lambda s: default_filter(s) and s >= 0
     unary_assert_against_refimpl(
-        "sqrt", x, out, math.sqrt, filter_=lambda s: default_filter(s) and s >= 0
+        "sqrt", x, out, refimpl, filter_=filter_
     )
 
 
@@ -1605,15 +1673,17 @@ def test_tan(x):
     out = xp.tan(x)
     ph.assert_dtype("tan", in_dtype=x.dtype, out_dtype=out.dtype)
     ph.assert_shape("tan", out_shape=out.shape, expected=x.shape)
-    unary_assert_against_refimpl("tan", x, out, math.tan)
+    refimpl = cmath.tan if x.dtype in dh.complex_dtypes else math.tan
+    unary_assert_against_refimpl("tan", x, out, refimpl)
 
 
 @given(hh.arrays(dtype=hh.all_floating_dtypes(), shape=hh.shapes()))
 def test_tanh(x):
     out = xp.tanh(x)
     ph.assert_dtype("tanh", in_dtype=x.dtype, out_dtype=out.dtype)
     ph.assert_shape("tanh", out_shape=out.shape, expected=x.shape)
-    unary_assert_against_refimpl("tanh", x, out, math.tanh)
+    refimpl = cmath.tanh if x.dtype in dh.complex_dtypes else math.tanh
+    unary_assert_against_refimpl("tanh", x, out, refimpl)
 
 
 @given(hh.arrays(dtype=hh.real_dtypes, shape=xps.array_shapes()))