René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"\\genfrac should accept a unit for thickness","articleBody":"In LaTeX, the third parameter (bar thickness) to `genfrac` requires a unit, but Matplotlib's mathtext parser does not accept it. This causes an inconsistency in the docs between Matplotlib and LaTeX, cf https://github.com/matplotlib/matplotlib/pull/18948/files#diff-9d1b2ab4b8a5e77dc635425c7e7ec00af5667d684d0809e46a973185e8f9918fR97\r\n\r\n**Code for reproduction**\r\n\r\n```python\r\nimport matplotlib.pyplot as plt\r\n\r\nplt.text(0, 0, r'$\\genfrac{(}{)}{3pt}{0}{foo}{bar}$')\r\nplt.draw()\r\n```\r\n\r\n**Actual outcome**\r\n\r\n```pytb\r\nTraceback (most recent call last):\r\n  File \"/usr/lib64/python3.8/tkinter/__init__.py\", line 1883, in __call__\r\n    return self.func(*args)\r\n  File \"/usr/lib64/python3.8/tkinter/__init__.py\", line 804, in callit\r\n    func(*args)\r\n  File \"/usr/lib64/python3.8/site-packages/matplotlib/backends/_backend_tk.py\", line 270, in idle_draw\r\n    self.draw()\r\n  File \"/usr/lib64/python3.8/site-packages/matplotlib/backends/backend_tkagg.py\", line 9, in draw\r\n    super(FigureCanvasTkAgg, self).draw()\r\n  File \"/usr/lib64/python3.8/site-packages/matplotlib/backends/backend_agg.py\", line 393, in draw\r\n    self.figure.draw(self.renderer)\r\n  File \"/usr/lib64/python3.8/site-packages/matplotlib/artist.py\", line 38, in draw_wrapper\r\n    return draw(artist, renderer, *args, **kwargs)\r\n  File \"/usr/lib64/python3.8/site-packages/matplotlib/figure.py\", line 1735, in draw\r\n    mimage._draw_list_compositing_images(\r\n  File \"/usr/lib64/python3.8/site-packages/matplotlib/image.py\", line 137, in _draw_list_compositing_images\r\n    a.draw(renderer)\r\n  File \"/usr/lib64/python3.8/site-packages/matplotlib/artist.py\", line 38, in draw_wrapper\r\n    return draw(artist, renderer, *args, **kwargs)\r\n  File \"/usr/lib64/python3.8/site-packages/matplotlib/axes/_base.py\", line 2630, in draw\r\n    mimage._draw_list_compositing_images(renderer, self, artists)\r\n  File \"/usr/lib64/python3.8/site-packages/matplotlib/image.py\", line 137, in _draw_list_compositing_images\r\n    a.draw(renderer)\r\n  File \"/usr/lib64/python3.8/site-packages/matplotlib/artist.py\", line 38, in draw_wrapper\r\n    return draw(artist, renderer, *args, **kwargs)\r\n  File \"/usr/lib64/python3.8/site-packages/matplotlib/text.py\", line 685, in draw\r\n    bbox, info, descent = textobj._get_layout(renderer)\r\n  File \"/usr/lib64/python3.8/site-packages/matplotlib/text.py\", line 299, in _get_layout\r\n    w, h, d = renderer.get_text_width_height_descent(\r\n  File \"/usr/lib64/python3.8/site-packages/matplotlib/backends/backend_agg.py\", line 209, in get_text_width_height_descent\r\n    self.mathtext_parser.parse(s, self.dpi, prop)\r\n  File \"/usr/lib64/python3.8/site-packages/matplotlib/mathtext.py\", line 3354, in parse\r\n    box = self._parser.parse(s, font_output, fontsize, dpi)\r\n  File \"/usr/lib64/python3.8/site-packages/matplotlib/mathtext.py\", line 2583, in parse\r\n    raise ValueError(\"\\n\".join([\"\",\r\nValueError: \r\n\\genfrac{(}{)}{3pt}{0}{foo}{bar}\r\n        ^\r\nExpected \\genfrac{ldelim}{rdelim}{rulesize}{style}{num}{den}, found '{'  (at char 8), (line:1, col:9)\r\n```\r\n\r\n**Expected outcome**\r\n\r\nDraws as if passing `3` instead of `3pt`, though possibly slightly different spacing, as I'm not sure in what unit we treat the 3 right now.","author":{"url":"https://github.com/QuLogic","@type":"Person","name":"QuLogic"},"datePublished":"2020-11-24T06:31:26.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/19001/matplotlib/issues/19001"}