| 1 | n/a | from test.support import TestFailed |
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| 2 | n/a | |
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| 3 | n/a | # A test for SF bug 422177: manifest float constants varied way too much in |
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| 4 | n/a | # precision depending on whether Python was loading a module for the first |
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| 5 | n/a | # time, or reloading it from a precompiled .pyc. The "expected" failure |
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| 6 | n/a | # mode is that when test_import imports this after all .pyc files have been |
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| 7 | n/a | # erased, it passes, but when test_import imports this from |
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| 8 | n/a | # double_const.pyc, it fails. This indicates a woeful loss of precision in |
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| 9 | n/a | # the marshal format for doubles. It's also possible that repr() doesn't |
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| 10 | n/a | # produce enough digits to get reasonable precision for this box. |
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| 11 | n/a | |
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| 12 | n/a | PI = 3.14159265358979324 |
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| 13 | n/a | TWOPI = 6.28318530717958648 |
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| 14 | n/a | |
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| 15 | n/a | PI_str = "3.14159265358979324" |
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| 16 | n/a | TWOPI_str = "6.28318530717958648" |
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| 17 | n/a | |
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| 18 | n/a | # Verify that the double x is within a few bits of eval(x_str). |
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| 19 | n/a | def check_ok(x, x_str): |
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| 20 | n/a | assert x > 0.0 |
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| 21 | n/a | x2 = eval(x_str) |
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| 22 | n/a | assert x2 > 0.0 |
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| 23 | n/a | diff = abs(x - x2) |
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| 24 | n/a | # If diff is no larger than 3 ULP (wrt x2), then diff/8 is no larger |
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| 25 | n/a | # than 0.375 ULP, so adding diff/8 to x2 should have no effect. |
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| 26 | n/a | if x2 + (diff / 8.) != x2: |
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| 27 | n/a | raise TestFailed("Manifest const %s lost too much precision " % x_str) |
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| 28 | n/a | |
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| 29 | n/a | check_ok(PI, PI_str) |
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| 30 | n/a | check_ok(TWOPI, TWOPI_str) |
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