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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"ValueError for `math.atan2(0.0, 0.0)` and `cmath.phase(0.0)` using icx","articleBody":"# Bug report\n\n### Bug description:\n\nThe math function `atan2` and the cmath function `phase` should not raise ValueError when their arguments are zero.  This is true when building CPython using an officially supported compiler such as GCC:\n\n```python\n\u003e\u003e\u003e import math\n\u003e\u003e\u003e import cmath\n\u003e\u003e\u003e math.atan2(0.0, 0.0)\n0.0\n\u003e\u003e\u003e cmath.phase(complex(0.0, 0.0))\n0.0\n\u003e\u003e\u003e math.atan2(0.0, -0.0)\n3.141592653589793\n\u003e\u003e\u003e cmath.phase(complex(-0.0, 0.0))\n3.141592653589793\n```\n\nHowever, The C23 standard (ISO/IEC 9899:2024) in section 7.12.4.4 for `atan2` states:\n\u003e A domain error may occur if both arguments are zero.\n\nThe Intel math library version 2026.0.0 sets `errno` to `EDOM` for these cases.  See also PR #152825.  Thus:\n```python\n\u003e\u003e\u003e import math\n\u003e\u003e\u003e import cmath\n\u003e\u003e\u003e math.atan2(0.0, 0.0)\nTraceback (most recent call last):\n  File \"\u003cpython-input-2\u003e\", line 1, in \u003cmodule\u003e\n    math.atan2(0.0, 0.0)\n    ~~~~~~~~~~^^^^^^^^^^\nValueError: math domain error\n\u003e\u003e\u003e cmath.phase(complex(0.0, 0.0))\nTraceback (most recent call last):\n  File \"\u003cpython-input-3\u003e\", line 1, in \u003cmodule\u003e\n    cmath.phase(complex(0.0, 0.0))\n    ~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^\nValueError: math domain error\n\u003e\u003e\u003e math.atan2(0.0, -0.0)\nTraceback (most recent call last):\n  File \"\u003cpython-input-4\u003e\", line 1, in \u003cmodule\u003e\n    math.atan2(0.0, -0.0)\n    ~~~~~~~~~~^^^^^^^^^^^\nValueError: math domain error\n\u003e\u003e\u003e cmath.phase(complex(-0.0, 0.0))\nTraceback (most recent call last):\n  File \"\u003cpython-input-5\u003e\", line 1, in \u003cmodule\u003e\n    cmath.phase(complex(-0.0, 0.0))\n    ~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^\nValueError: math domain error\n```\n\n### CPython versions tested on:\n\nCPython main branch\n\n### Operating systems tested on:\n\nLinux\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-153148\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/hpkfft","@type":"Person","name":"hpkfft"},"datePublished":"2026-07-05T18:58:59.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":10},"url":"https://github.com/153144/cpython/issues/153144"}