René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"`SymLogNorm` and `SymLogScale` give inconsistent results....","articleBody":"on master....\r\n\r\n```python\r\nimport matplotlib.pyplot as plt\r\nimport numpy as np\r\nimport matplotlib.scale as mscale\r\nimport matplotlib.colors as mcolors\r\n\r\n#scale = mscale.SymmetricalLogScale(ax.xaxis, linthreshx=1.0)\r\nfig, ax =plt.subplots()\r\nax.set_xscale('symlog', linthreshx=1.0, linscale=1)\r\n\r\nax.plot(np.arange(-100, 100, 0.1), np.arange(-100, 100, 0.1))\r\nax.set_xlim([-100, 100])\r\nscale = ax.xaxis._scale\r\n\r\nnorm = mcolors.SymLogNorm(linthresh=1.0, linscale=1, vmin=-100, vmax=100)\r\nxx = scale._transform.transform([-200, -100, -10, -1, -0.5, 0, 0.5, 1, 10, 100, 200])\r\n\r\nprint((xx - xx[1])/(xx[-2] - xx[1]))\r\nprint(norm([-200, -100, -10, -1, -0.5, 0, 0.5, 1, 10, 100, 200]))\r\n\r\n\r\nfig, ax = plt.subplots()\r\nax.plot(norm([-200, -100, -10, -1, -0.5, 0, 0.5, 1, 10, 100, 200]), xx, '.')\r\nax.set_xlabel('Norm')\r\nax.set_ylabel('Scale')\r\n```\r\n\r\nyields\r\n\r\n```\r\n[-0.0483798207317112 0.0 0.1607142857142857 0.3214285714285714\r\n 0.4107142857142857 0.5 0.5892857142857143 0.6785714285714286\r\n 0.8392857142857143 1.0 1.0483798207317112]   # scale\r\n[-0.05601509  0.          0.1860781   0.3721562   0.4360781   0.5\r\n  0.5639219   0.6278438   0.8139219   1.          1.05601509]  # Norm\r\n```\r\n\r\nI think scale is right, and norm is wrong...\r\n\r\n![NormIssue2](https://user-images.githubusercontent.com/1562854/73495747-06553d80-436c-11ea-8631-1544dc40c767.png)\r\n\r\n\r\n![NormIssue](https://user-images.githubusercontent.com/1562854/73495719-f4739a80-436b-11ea-9051-b698af5e8925.png)\r\n","author":{"url":"https://github.com/jklymak","@type":"Person","name":"jklymak"},"datePublished":"2020-01-30T22:23:29.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":10},"url":"https://github.com/16376/matplotlib/issues/16376"}