Merge pull request numpy#24448 from WarrenWeckesser/test-complex-log

TST: add some tests of np.log for complex input.

Author: mattip

numpy/_core/src/common/npy_config.h

@@ -126,6 +126,14 @@
 #undef HAVE_CPOWL
 #undef HAVE_CEXPL
 
+/*
+ * cygwin uses newlib, which has naive implementations of the
+ * complex log functions.
+ */
+#undef HAVE_CLOG
+#undef HAVE_CLOGF
+#undef HAVE_CLOGL
+
 #include <cygwin/version.h>
 #if CYGWIN_VERSION_DLL_MAJOR < 3003
 // rather than blocklist cabsl, hypotl, modfl, sqrtl, error out
@@ -182,6 +190,16 @@
 #undef HAVE_CACOSHF
 #undef HAVE_CACOSHL
 
+/*
+ * musl's clog is low precision for some inputs.  As of MUSL 1.2.5,
+ * the first comment in clog.c is "// FIXME".
+ * See https://github.com/numpy/numpy/pull/24416#issuecomment-1678208628
+ * and https://github.com/numpy/numpy/pull/24448
+ */
+#undef HAVE_CLOG
+#undef HAVE_CLOGF
+#undef HAVE_CLOGL
+
 #endif  /* defined(__GLIBC) */
 #endif  /* defined(HAVE_FEATURES_H) */
 

numpy/_core/tests/test_umath.py

@@ -1404,6 +1404,36 @@ def test_log_strides(self):
                 assert_array_almost_equal_nulp(np.log(x_f64[::jj]), y_true[::jj], nulp=2)
                 assert_array_almost_equal_nulp(np.log(x_special[::jj]), y_special[::jj], nulp=2)
 
+    # Reference values were computed with mpmath, with mp.dps = 200.
+    @pytest.mark.parametrize(
+        'z, wref',
+        [(1 + 1e-12j, 5e-25 + 1e-12j),
+         (1.000000000000001 + 3e-08j,
+          1.5602230246251546e-15 + 2.999999999999996e-08j),
+         (0.9999995000000417 + 0.0009999998333333417j,
+          7.831475869017683e-18 + 0.001j),
+         (0.9999999999999996 + 2.999999999999999e-08j,
+          5.9107901499372034e-18 + 3e-08j),
+         (0.99995000042 - 0.009999833j,
+          -7.015159763822903e-15 - 0.009999999665816696j)],
+    )
+    def test_log_precision_float64(self, z, wref):
+        w = np.log(z)
+        assert_allclose(w, wref, rtol=1e-15)
+
+    # Reference values were computed with mpmath, with mp.dps = 200.
+    @pytest.mark.parametrize(
+        'z, wref',
+        [(np.complex64(1.0 + 3e-6j), np.complex64(4.5e-12+3e-06j)),
+         (np.complex64(1.0 - 2e-5j), np.complex64(1.9999999e-10 - 2e-5j)),
+         (np.complex64(0.9999999 + 1e-06j),
+          np.complex64(-1.192088e-07+1.0000001e-06j))],
+    )
+    def test_log_precision_float32(self, z, wref):
+        w = np.log(z)
+        assert_allclose(w, wref, rtol=1e-6)
+
+
 class TestExp:
     def test_exp_values(self):
         x = [1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024]