init

2026-02-12 23:22:11 +08:00
parent 7b09eb3d89
commit 89660bba4e
5988 changed files with 2517516 additions and 0 deletions
@@ -0,0 +1,89 @@
+import numpy as np
+from numpy.testing import assert_allclose, assert_equal
+import pytest
+
+import scipy.special as sc
+
+
+class TestInverseErrorFunction:
+    def test_compliment(self):
+        # Test erfcinv(1 - x) == erfinv(x)
+        x = np.linspace(-1, 1, 101)
+        assert_allclose(sc.erfcinv(1 - x), sc.erfinv(x), rtol=0, atol=1e-15)
+
+    def test_literal_values(self):
+        # The expected values were calculated with mpmath:
+        #
+        #   import mpmath
+        #   mpmath.mp.dps = 200
+        #   for y in [0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9]:
+        #       x = mpmath.erfinv(y)
+        #       print(x)
+        #
+        y = np.array([0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9])
+        actual = sc.erfinv(y)
+        expected = [
+            0.0,
+            0.08885599049425769,
+            0.1791434546212917,
+            0.2724627147267543,
+            0.37080715859355795,
+            0.4769362762044699,
+            0.5951160814499948,
+            0.7328690779592167,
+            0.9061938024368233,
+            1.1630871536766743,
+        ]
+        assert_allclose(actual, expected, rtol=0, atol=1e-15)
+
+    @pytest.mark.parametrize(
+        'f, x, y',
+        [
+            (sc.erfinv, -1, -np.inf),
+            (sc.erfinv, 0, 0),
+            (sc.erfinv, 1, np.inf),
+            (sc.erfinv, -100, np.nan),
+            (sc.erfinv, 100, np.nan),
+            (sc.erfcinv, 0, np.inf),
+            (sc.erfcinv, 1, -0.0),
+            (sc.erfcinv, 2, -np.inf),
+            (sc.erfcinv, -100, np.nan),
+            (sc.erfcinv, 100, np.nan),
+        ],
+        ids=[
+            'erfinv at lower bound',
+            'erfinv at midpoint',
+            'erfinv at upper bound',
+            'erfinv below lower bound',
+            'erfinv above upper bound',
+            'erfcinv at lower bound',
+            'erfcinv at midpoint',
+            'erfcinv at upper bound',
+            'erfcinv below lower bound',
+            'erfcinv above upper bound',
+        ]
+    )
+    def test_domain_bounds(self, f, x, y):
+        assert_equal(f(x), y)
+
+    def test_erfinv_asympt(self):
+        # regression test for gh-12758: erfinv(x) loses precision at small x
+        # expected values precomputed with mpmath:
+        # >>> mpmath.mp.dps = 100
+        # >>> expected = [float(mpmath.erfinv(t)) for t in x]
+        x = np.array([1e-20, 1e-15, 1e-14, 1e-10, 1e-8, 0.9e-7, 1.1e-7, 1e-6])
+        expected = np.array([8.86226925452758e-21,
+                             8.862269254527581e-16,
+                             8.86226925452758e-15,
+                             8.862269254527581e-11,
+                             8.86226925452758e-09,
+                             7.97604232907484e-08,
+                             9.74849617998037e-08,
+                             8.8622692545299e-07])
+        assert_allclose(sc.erfinv(x), expected,
+                        rtol=1e-15)
+
+        # also test the roundtrip consistency
+        assert_allclose(sc.erf(sc.erfinv(x)),
+                        x,
+                        rtol=5e-15)