BUG: fix cpow tests to match what npy_cpow does.

ewmoore · ewmoore · commit eab5228ac6d3 · 2014-02-26T18:11:27.000-05:00
Annex G of the C99 standard does not define any special values for cpow,
allowing the implementation to be as simple as cpow(z,w) =
cexp(w*clog(z)).  We have a large number of tests for our cpow function,
both in the test suite and in test_c99complex.c. (There are actually
more in test_c99complex.c, since I'm doing all combinations from
TestCpow::test_scalar in test_umath_complex.py.)

As of right now, these tests probably mean that we will never use a
system cpow implemenation. This is fine, since we handle a large number
of edge cases in a sane way and at least glibc does not.

With this commit all 48 of our complex functions pass test_c99complex.c.
diff --git a/numpy/core/test_c99complex.c b/numpy/core/test_c99complex.c
@@ -1458,7 +1458,7 @@ int test_cpow()
 
     TEST_CPOW_CC(0, 1, 1, 0, 0, 1);
     TEST_CPOW_CC(0, 1, 0, 1, ADDSUFFIX(exp)(-NPY_PI_2), 0);
-    TEST_CPOW_CC(0, 1, -0.5, 1.5, 0.067019739708273365, 0.067019739708273365);
+    TEST_CPOW_CC(0, 1, -0.5, 1.5, 0.067019739708273365, -0.067019739708273365);
     TEST_CPOW_CC(0, 1, 2, 0, -1, 0);
     TEST_CPOW_CC(0, 1, 3, 0, 0, -1);
 
@@ -1473,13 +1473,13 @@ int test_cpow()
     TEST_CPOW_CC(2.5, 0.375, 2, 0, 391.0/64.0, 15.0/8.0);
     TEST_CPOW_CC(2.5, 0.375, 3, 0, 1865.0/128.0, 3573.0/512.0);
 
-    TEST_CPOW_EE(INFINITY, 0, 1, 0, NAN, NAN);
+    TEST_CPOW_EE(INFINITY, 0, 1, 0, INFINITY, 0);
     TEST_CPOW_EE(INFINITY, 0, 0, 1, NAN, NAN);
-    TEST_CPOW_EE(INFINITY, 0, -0.5, 1.5, NAN, NAN);
-    TEST_CPOW_EE(INFINITY, 0, 2, 0, NAN, NAN);
+    TEST_CPOW_EE(INFINITY, 0, -0.5, 1.5, 0, 0);
+    TEST_CPOW_EE(INFINITY, 0, 2, 0, INFINITY, NAN);
     TEST_CPOW_EE(INFINITY, 0, 3, 0, NAN, NAN);
 
-    TEST_CPOW_EE(NAN, 0, 1, 0, NAN, NAN);
+    TEST_CPOW_EE(NAN, 0, 1, 0, NAN, 0);
     TEST_CPOW_EE(NAN, 0, 0, 1, NAN, NAN);
     TEST_CPOW_EE(NAN, 0, -0.5, 1.5, NAN, NAN);
     TEST_CPOW_EE(NAN, 0, 2, 0, NAN, NAN);
