--- /dev/null Thu Jan 01 00:00:00 1970 +0000 |
+++ b/Modules/_decimal/tests/randfloat.py Sat Mar 10 18:12:20 2012 +0100 |
@@ -0,0 +1,250 @@ |
+# Copyright (c) 2010 Python Software Foundation. All Rights Reserved. |
+# Adapted from Python's Lib/test/test_strtod.py (by Mark Dickinson) |
+ |
+# More test cases for deccheck.py. |
+ |
+import random |
+ |
+TEST_SIZE = 2 |
+ |
+ |
+def test_short_halfway_cases(): |
+ # exact halfway cases with a small number of significant digits |
+ for k in 0, 5, 10, 15, 20: |
+ # upper = smallest integer >= 2**54/5**k |
+ upper = -(-2**54//5**k) |
+ # lower = smallest odd number >= 2**53/5**k |
+ lower = -(-2**53//5**k) |
+ if lower % 2 == 0: |
+ lower += 1 |
+ for i in range(10 * TEST_SIZE): |
+ # Select a random odd n in [2**53/5**k, |
+ # 2**54/5**k). Then n * 10**k gives a halfway case |
+ # with small number of significant digits. |
+ n, e = random.randrange(lower, upper, 2), k |
+ |
+ # Remove any additional powers of 5. |
+ while n % 5 == 0: |
+ n, e = n // 5, e + 1 |
+ assert n % 10 in (1, 3, 7, 9) |
+ |
+ # Try numbers of the form n * 2**p2 * 10**e, p2 >= 0, |
+ # until n * 2**p2 has more than 20 significant digits. |
+ digits, exponent = n, e |
+ while digits < 10**20: |
+ s = '{}e{}'.format(digits, exponent) |
+ yield s |
+ # Same again, but with extra trailing zeros. |
+ s = '{}e{}'.format(digits * 10**40, exponent - 40) |
+ yield s |
+ digits *= 2 |
+ |
+ # Try numbers of the form n * 5**p2 * 10**(e - p5), p5 |
+ # >= 0, with n * 5**p5 < 10**20. |
+ digits, exponent = n, e |
+ while digits < 10**20: |
+ s = '{}e{}'.format(digits, exponent) |
+ yield s |
+ # Same again, but with extra trailing zeros. |
+ s = '{}e{}'.format(digits * 10**40, exponent - 40) |
+ yield s |
+ digits *= 5 |
+ exponent -= 1 |
+ |
+def test_halfway_cases(): |
+ # test halfway cases for the round-half-to-even rule |
+ for i in range(1000): |
+ for j in range(TEST_SIZE): |
+ # bit pattern for a random finite positive (or +0.0) float |
+ bits = random.randrange(2047*2**52) |
+ |
+ # convert bit pattern to a number of the form m * 2**e |
+ e, m = divmod(bits, 2**52) |
+ if e: |
+ m, e = m + 2**52, e - 1 |
+ e -= 1074 |
+ |
+ # add 0.5 ulps |
+ m, e = 2*m + 1, e - 1 |
+ |
+ # convert to a decimal string |
+ if e >= 0: |
+ digits = m << e |
+ exponent = 0 |
+ else: |
+ # m * 2**e = (m * 5**-e) * 10**e |
+ digits = m * 5**-e |
+ exponent = e |
+ s = '{}e{}'.format(digits, exponent) |
+ yield s |
+ |
+def test_boundaries(): |
+ # boundaries expressed as triples (n, e, u), where |
+ # n*10**e is an approximation to the boundary value and |
+ # u*10**e is 1ulp |
+ boundaries = [ |
+ (10000000000000000000, -19, 1110), # a power of 2 boundary (1.0) |
+ (17976931348623159077, 289, 1995), # overflow boundary (2.**1024) |
+ (22250738585072013831, -327, 4941), # normal/subnormal (2.**-1022) |
+ (0, -327, 4941), # zero |
+ ] |
+ for n, e, u in boundaries: |
+ for j in range(1000): |
+ for i in range(TEST_SIZE): |
+ digits = n + random.randrange(-3*u, 3*u) |
+ exponent = e |
+ s = '{}e{}'.format(digits, exponent) |
+ yield s |
+ n *= 10 |
+ u *= 10 |
+ e -= 1 |
+ |
+def test_underflow_boundary(): |
+ # test values close to 2**-1075, the underflow boundary; similar |
+ # to boundary_tests, except that the random error doesn't scale |
+ # with n |
+ for exponent in range(-400, -320): |
+ base = 10**-exponent // 2**1075 |
+ for j in range(TEST_SIZE): |
+ digits = base + random.randrange(-1000, 1000) |
+ s = '{}e{}'.format(digits, exponent) |
+ yield s |
+ |
+def test_bigcomp(): |
+ for ndigs in 5, 10, 14, 15, 16, 17, 18, 19, 20, 40, 41, 50: |
+ dig10 = 10**ndigs |
+ for i in range(100 * TEST_SIZE): |
+ digits = random.randrange(dig10) |
+ exponent = random.randrange(-400, 400) |
+ s = '{}e{}'.format(digits, exponent) |
+ yield s |
+ |
+def test_parsing(): |
+ # make '0' more likely to be chosen than other digits |
+ digits = '000000123456789' |
+ signs = ('+', '-', '') |
+ |
+ # put together random short valid strings |
+ # \d*[.\d*]?e |
+ for i in range(1000): |
+ for j in range(TEST_SIZE): |
+ s = random.choice(signs) |
+ intpart_len = random.randrange(5) |
+ s += ''.join(random.choice(digits) for _ in range(intpart_len)) |
+ if random.choice([True, False]): |
+ s += '.' |
+ fracpart_len = random.randrange(5) |
+ s += ''.join(random.choice(digits) |
+ for _ in range(fracpart_len)) |
+ else: |
+ fracpart_len = 0 |
+ if random.choice([True, False]): |
+ s += random.choice(['e', 'E']) |
+ s += random.choice(signs) |
+ exponent_len = random.randrange(1, 4) |
+ s += ''.join(random.choice(digits) |
+ for _ in range(exponent_len)) |
+ |
+ if intpart_len + fracpart_len: |
+ yield s |
+ |
+test_particular = [ |
+ # squares |
+ '1.00000000100000000025', |
+ '1.0000000000000000000000000100000000000000000000000' #... |
+ '00025', |
+ '1.0000000000000000000000000000000000000000000010000' #... |
+ '0000000000000000000000000000000000000000025', |
+ '1.0000000000000000000000000000000000000000000000000' #... |
+ '000001000000000000000000000000000000000000000000000' #... |
+ '000000000025', |
+ '0.99999999900000000025', |
+ '0.9999999999999999999999999999999999999999999999999' #... |
+ '999000000000000000000000000000000000000000000000000' #... |
+ '000025', |
+ '0.9999999999999999999999999999999999999999999999999' #... |
+ '999999999999999999999999999999999999999999999999999' #... |
+ '999999999999999999999999999999999999999990000000000' #... |
+ '000000000000000000000000000000000000000000000000000' #... |
+ '000000000000000000000000000000000000000000000000000' #... |
+ '0000000000000000000000000000025', |
+ |
+ '1.0000000000000000000000000000000000000000000000000' #... |
+ '000000000000000000000000000000000000000000000000000' #... |
+ '100000000000000000000000000000000000000000000000000' #... |
+ '000000000000000000000000000000000000000000000000001', |
+ '1.0000000000000000000000000000000000000000000000000' #... |
+ '000000000000000000000000000000000000000000000000000' #... |
+ '500000000000000000000000000000000000000000000000000' #... |
+ '000000000000000000000000000000000000000000000000005', |
+ '1.0000000000000000000000000000000000000000000000000' #... |
+ '000000000100000000000000000000000000000000000000000' #... |
+ '000000000000000000250000000000000002000000000000000' #... |
+ '000000000000000000000000000000000000000000010000000' #... |
+ '000000000000000000000000000000000000000000000000000' #... |
+ '0000000000000000001', |
+ '1.0000000000000000000000000000000000000000000000000' #... |
+ '000000000100000000000000000000000000000000000000000' #... |
+ '000000000000000000249999999999999999999999999999999' #... |
+ '999999999999979999999999999999999999999999999999999' #... |
+ '999999999999999999999900000000000000000000000000000' #... |
+ '000000000000000000000000000000000000000000000000000' #... |
+ '00000000000000000000000001', |
+ |
+ '0.9999999999999999999999999999999999999999999999999' #... |
+ '999999999900000000000000000000000000000000000000000' #... |
+ '000000000000000000249999999999999998000000000000000' #... |
+ '000000000000000000000000000000000000000000010000000' #... |
+ '000000000000000000000000000000000000000000000000000' #... |
+ '0000000000000000001', |
+ '0.9999999999999999999999999999999999999999999999999' #... |
+ '999999999900000000000000000000000000000000000000000' #... |
+ '000000000000000000250000001999999999999999999999999' #... |
+ '999999999999999999999999999999999990000000000000000' #... |
+ '000000000000000000000000000000000000000000000000000' #... |
+ '1', |
+ |
+ # tough cases for ln etc. |
+ '1.000000000000000000000000000000000000000000000000' #... |
+ '00000000000000000000000000000000000000000000000000' #... |
+ '00100000000000000000000000000000000000000000000000' #... |
+ '00000000000000000000000000000000000000000000000000' #... |
+ '0001', |
+ '0.999999999999999999999999999999999999999999999999' #... |
+ '99999999999999999999999999999999999999999999999999' #... |
+ '99899999999999999999999999999999999999999999999999' #... |
+ '99999999999999999999999999999999999999999999999999' #... |
+ '99999999999999999999999999999999999999999999999999' #... |
+ '9999' |
+ ] |
+ |
+ |
+TESTCASES = [ |
+ [x for x in test_short_halfway_cases()], |
+ [x for x in test_halfway_cases()], |
+ [x for x in test_boundaries()], |
+ [x for x in test_underflow_boundary()], |
+ [x for x in test_bigcomp()], |
+ [x for x in test_parsing()], |
+ test_particular |
+] |
+ |
+def un_randfloat(): |
+ for i in range(1000): |
+ l = random.choice(TESTCASES[:6]) |
+ yield random.choice(l) |
+ for v in test_particular: |
+ yield v |
+ |
+def bin_randfloat(): |
+ for i in range(1000): |
+ l1 = random.choice(TESTCASES) |
+ l2 = random.choice(TESTCASES) |
+ yield random.choice(l1), random.choice(l2) |
+ |
+def tern_randfloat(): |
+ for i in range(1000): |
+ l1 = random.choice(TESTCASES) |
+ l2 = random.choice(TESTCASES) |
+ l3 = random.choice(TESTCASES) |
+ yield random.choice(l1), random.choice(l2), random.choice(l3) |